Golf ball incorporating compression molded layer and methods and tooling for making

ABSTRACT

Method of making an inventive golf ball incorporating a novel compression molded outer layer comprised of inventive first and second half-shells that are molded from preforms of extrudate, each preform created using a novel flying knife such that a cross-sectioned face of the preform has a curved depth which may be up to 20% greater than the depth of a preform created using a conventional straight edge and/or straight-faced flying knife. In one embodiment, the subassembly of the golf ball is a rubber spherical inner core, and the inventive compression molded outer layer is a rubber outer core layer. In a specific such embodiment, the rubber of the inner core and the rubber of the outer core layer differ.

FIELD OF THE INVENTION

Golf balls having and displaying excellent concentricity between asubassembly and outer layer compression molded thereabout.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general classes: solidand wound. Solid golf balls include one-piece, two-piece (i.e., singlelayer core and single layer cover), and multi-layer (i.e., solid core ofone or more layers and/or a cover of one or more layers) golf balls.Wound golf balls typically include a solid, hollow, or fluid-filledcenter, surrounded by a tensioned elastomeric material, and a cover.

Examples of golf ball materials range from rubber materials, such asbalata, styrene butadiene, polybutadiene, or polyisoprene, tothermoplastic or thermoset resins such as ionomers, polyolefins,polyamides, polyesters, polyurethanes, polyureas and/orpolyurethane/polyurea hybrids, and blends thereof. Typically, outerlayers are formed about the spherical outer surface of an innermost golfball layer via compression molding, casting, or injection molding.

From the perspective of a golf ball manufacturer, it is desirable tohave materials exhibiting a wide range of properties, such asresilience, durability, spin, and “feel,” because this enables themanufacturer to make and sell golf balls suited to differing levels ofability and/or preferences. In this regard, playing characteristics ofgolf balls, such as spin, feel, CoR and compression can be tailored byvarying the properties of the golf ball materials and/or addingadditional golf ball layers such as at least one intermediate layerdisposed between the cover and the core. Intermediate layers can be ofsolid construction, and have also been formed of a tensioned elastomericwinding. The difference in play characteristics resulting from thesedifferent types of constructions can be quite significant.

Golf balls are generally made by forming outer layers about an interiorlayer via one or more of injection molding, casting and compressionmolding. Compression molding typically involves cross-sectioning alength of extrudate into a plurality of preforms/slugs, molding thepreforms/slugs into half-shells, and then mating a pair of half-shellsabout each preform/slug under sufficient heat and pressure.

Heretofore, lengths of extrudate have been cross-sectioned atpredetermined intervals by a rotating straight-edge flying knife-typeblade while the extrudate progresses on an assembly line in a directionthat is perpendicular to the direction that the straight-edge flyingknife-type blade is rotating. Examples of such a conventionalstraight-edged flying knife-type blade include blade 3 of FIG. 1B,discussed herein below, and/or blade 22 of U.S. Pat. No. 5,596,251 ofMiller (“'251 patent”)(for cutting molten plastic material), herebyincorporated herein in its entirety.

The resulting conventional preforms have cross-sectioned faces that areflat/level to very slightly curved due to forces which act on theextrudate as it progresses along the assembly during cross-sectioning.This flat/level to very slightly curved surface contour changessubstantially while being molded into a cup-shaped half-shell.

Unfortunately, such preforms can fill out in the mold unsatisfactorilywhile making this big shape adjustment and produce a half-shells havingirregularities such as a non-uniform thickness. And when thosehalf-shells are then compression molded about a subassembly, thesubassembly can be off-center, which negatively impacts golf ball flightand putting characteristics as well as creates golf ball durabilityproblems.

Accordingly, there is a need for improved preform face shapes that moreclosely match, follow or resemble the ultimate cup-shaped contour of ahalf-shell which would reduce the amount of change a preform has toundergo while being molded into a half-shell. Such preforms, and methodsof making, if meanwhile producible and implementable within existingcompression molding and golf ball manufacturing processes, would beparticularly desirable and useful. The accompanying inventive golfballs, preforms, half-shells, tooling and methods of making same addressand solve this need.

SUMMARY OF THE INVENTION

The invention therefore relates to a method of making a golf ballincorporating inventive half-shells that are comprised of inventivelyshaped preforms which are created using improved tooling—all desirablyimplementable within existing compression molding and golf ballmanufacturing processes. The method of making the inventive golf ballcomprises the steps of: (i) providing a length of extrudate having awidth sufficient to be received within first and second half-shellmolding cups; (ii) cross-sectioning the extrudate at predeterminedintervals along the length while progressing the extrudate along a planethat is perpendicular to a plane of rotation of a curved flying knifeand forming a plurality of preforms, each having a cross-sectionedsurface that is concave and curves inward toward a posterior end of thepreform a curved depth that is greater than a depth created by astraight edge flying knife; (iii) depositing first and second preformsinto a golf ball component mold, loading the mold into a mold press,closing the mold press and forming first and second half-shell moldingcups under sufficient heat and pressure; wherein the cross-sectionedsurfaces of the first and second preforms are face up in the golf ballcomponent mold and form an inner surface of each half shell molding cup;and (iv) mating first and second half-shell molding cups about asubassembly under sufficient heat and pressure.

In this regard, the curved flying knife may comprise (a) an elongatedbody defining an inner end and a distal end; the inner end beingrotatably connectable to a device for cross-sectioning a length ofextrudate into a plurality of preforms; and (b) a curved edge located ona first side of the elongated body and an opposing edge located on theopposite side of the elongated body; wherein each of the curved edge andthe opposing edge extend between the inner end and distal end; andwherein the curved edge curves away from the opposing edge at least at alocation on the first side that contacts the extrudate andcross-sections it.

In another embodiment, the curved flying knife may comprise: (a) anelongated body defining an inner end and a distal end; the inner endbeing rotatably connectable to a device for cross-sectioning a length ofextrudate into a plurality of preforms; and (b) a curved face located onthe elongated body between a bladed edge and an opposing edge; whereineach of the bladed edge and the opposing edge co-extend from the distalend toward the inner end a predetermined length and follow the contourof the curved face; and wherein the curved face curves toward theextrudate while the bladed edge cross-sections the extrudate.

In this embodiment, the bladed edge may be straight edged, oralternatively, have a curved edge that curves away from the opposingedge and contacts the extrudate and cross-sections it.

The curved depth may be greater than the depth by up to 20%.

In one embodiment, the subassembly is a rubber inner core and the outerlayer is a rubber outer core layer. In one such embodiment, the rubberof the inner core and the rubber of the outer core layer differ.

The invention also relates to a golf ball comprising a sphericalsubassembly surrounded by an outer layer comprised of first and secondcompression molded half-shell molding cups comprised of preforms ofrubber extrudate that are formed using a curved edge flying knife andhave first and second cross-sectioned surfaces each which curve inwardtoward a posterior end of the preform and have a curved depth that isgreater than a depth created by a straight edge flying knife.

The curved depth may be greater than the depth by up to 20%. In oneembodiment, the subassembly is a rubber inner core and the outer layeris a rubber outer core layer. In a specific such embodiment, the rubberof the inner core and the rubber of the outer core layer differ.

The invention further relates to a curved flying knife having: (a) anelongated body defining an inner end and a distal end; wherein the innerend is rotatably connectable to a device for creating a plurality ofpreforms from at least one length of extrudate; (b) a curved edgelocated on a first side of the elongated body and an opposing edgelocated on the opposite side of the elongated body; wherein each of thecurved edge and the opposing edge extend between the inner end anddistal end; and wherein the curved edge curves away from the opposingedge at least at a at a location on the first side that contacts theextrudate and cross-sections it and to a degree sufficient to create across-sectioned surface in each preform of extrudate that curves inwardtoward a posterior end of the preform and has a curved depth that isgreater than a depth created by a straight edge flying knife.

In a particular embodiment, the curved depth is greater than the depthby up to 20%.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention may be more fullyunderstood with reference to, but not limited by, the followingdrawings:

FIG. 1A is a representative side view of a curved flying knife of theinvention according to one embodiment;

FIG. 1B is a representative side view of a conventional straight edgeflying knife;

FIG. 1C is a representative side view of a curved flying knife of theinvention according to another embodiment;

FIG. 2A is a representative side view of a preform of the invention;

FIG. 2B is a representative side view of a conventional preform producedusing a conventional straight edge flying knife;

FIG. 3 is a representative side view of a pathway through which a curvedflying knife of the invention cross-sections a length of extrudate atpredetermined intervals as the extrudate progresses in a plane that isperpendicular to the plane of rotation of the curved flying knife;

FIG. 4A is a top view of a curved flying knife of the inventionaccording to one embodiment;

FIG. 4B is a top view of a curved flying knife of the inventionaccording to another embodiment;

FIG. 5A is a representative side view of a curved flying knife of theinvention according to yet another embodiment; and

FIG. 5B a representative side view of a curved flying knife of theinvention according to still another embodiment.

DETAILED DESCRIPTION

Advantageously, golf balls, preforms, half-shells, tooling and methodsof the invention significantly reduce the amount by which preform shapemust change while being molded into a half-shell and therefor alsoreduces the risk of poor concentricity occurring when a pair ofhalf-shells are compression molded about a subassembly. Preforms of theinvention have an improved surface contour constituting a bowl-shapedrecess which more closely resembles the ultimate cup-shaped contour of amolded half-shell. This preform construction improves the ability of apreform to fill out in the mold sufficient to create a half-shell havingreliably uniform thickness and better matability with an outer surfaceof the spherical subassembly about which a pair of half shells iscompression molded.

In this regard, the invention relates to a method of making the golfball comprising the steps of: (i) providing a length of extrudate havinga width sufficient to be received within first and second half-shellmolding cups; (ii) cross-sectioning the extrudate at predeterminedintervals along the length while progressing the extrudate along a planethat is perpendicular to a plane of rotation of a curved flying knifeand forming a plurality of preforms, each having a cross-sectionedsurface that is concave and curves inward toward a posterior end of thepreform a curved depth that is greater than a depth created by astraight edge flying knife; (iii) depositing first and second preformsinto a golf ball component mold and loading the mold into a mold press,closing the mold press and forming first and second half-shell moldingcups under sufficient heat and pressure, wherein the cross-sectionedsurfaces of the first and second preforms are face up in the mold andform an inner surface of each half shell molding cup; and (iv) matingfirst and second half-shell molding cups about a subassembly undersufficient heat and pressure.

As used herein, the terms cross-sectioning or cross-sectioned refer tocutting up a length of extrudate at predetermined intervals using aflying knife while the extrudate progresses along a plane that isperpendicular to a plane of rotation of the flying knife.

Moreover, the term “cross-sectioned surface”, as used herein, refers tothe contour created in the face of a preform using a flying knife asdescribed herein.

An inventive curved flying knife comprises (a) an elongated bodydefining an inner end and a distal end; the inner end being rotatablyconnectable to a device for cross-sectioning a length of extrudate intoa plurality of preforms; (b) a curved edge located on a first side ofthe elongated body and an opposing edge located on the opposite side ofthe elongated body; wherein each of the curved edge and the opposingedge extend between the inner end and distal end; and wherein the curvededge curves away from the opposing edge at least at a location on thefirst side that contacts the extrudate and cross-sections it.

The cross-sectioned surface curves inward toward a posterior end of thepreform a curved depth that is greater than a depth created by astraight edge flying knife and advantageously is produced by the curvedcontour of the curved edge flying knife. The curved blade creates apreform having better cut quality due to excellent engagement betweencurved edge flying knife and extrudate and better matability with theouter surface of a spherical inner core during compression molding thanprior preforms due at least in part to a cross-sectioned face which moreclosely follows or matches the contour of a resulting half shell innersurface.

In this regard, the curved edge of the curved edge flying knife has anarch that extends past the straight edge of the straight edge flyingknife a rise sufficient to produce up to 20% greater concavity andbowl-shaped recess in the resulting preform face than produced by thestraight edge of the straight edge flying knife having an otherwiseidentical design. That is, the curved depth created in an inventivepreform may be greater than the depth created by the straight edgeflying knife by up to 20% without extending engagement timeunnecessarily or interfering with engagement quality.

A straight edge blade can produce a preform having two ends withsubstantially level to slightly curved surfaces due to the forces actingon the extrudate as it progresses along the plane perpendicular to therotating direction of the straight edge blade. In contrast, the curveddepth of a preform of the invention will be up to 20% greater than thatcreated by an otherwise identical straight edge flying knife.

The extrudate may have any known length, but should have a width that issized to be received within the selected first and second half-shellmolding cups after the extrudate is cross-sectioned into preforms sincethe width or thickness of the extrudate is not modified bycross-sectioning.

Meanwhile, a curved flying knife of the invention has a larger bladevolume contacting the extrudate than would an otherwise identical priorstraight edge rotating flying knife due to the rise of the curved edgeflying knife (such as rise 12 of curved flying knife 2 depicted in FIG.1A—detailed below). Trying a curved edge flying knife iscounterintuitive because increasing blade volume increases engagementtime which has known to negatively impact cut quality and thereforemanufacturing time and cost.

One such inventive flying knife 2 is depicted in FIG. 1A and comparedwith conventional flying knife 3 of FIG. 1B. Inventive flying knife 2 ofFIG. 1A has a curved edge 4. In contrast, conventional flying knife 3 ofFIG. 1B has a straight edge 5. Each of curved edge 4 and straight edge 5are located on a first side 6 of an elongated body 7, which defines aninner end 8 and a distal end 9. Inner end 8 is rotatably connectable atlocation 10 to a device (not shown) for controlling and monitoringcross-sectioning of a length of extrudate into a plurality of preforms.An opposing edge 11 is located opposite first side 6 on elongated body 7and also between inner end 8 and distal end 9. In FIG. 1A, curved edge 4curves away from opposing edge 11 and has an arch 12 that creates rise13 extending from L₁ to L₂. L₁ illustrates where straight edge 5 is inotherwise identical straight edge flying knife 3 (see straight edge 5 inFIG. 1B).

Rise 13 of curved flying knife 1A is sufficient to create an inwardlycurved depth 14 in face 15 of inventive preform 16 of FIG. 2A duringcross-sectioning that is up to 20% greater than any depth 18 created inface 17 of conventional preform 19 of FIG. 2B (created by conventionalstraight edge flying knife 3 of FIG. 1B). Curved depth 14 in face 15 ofinventive preform 16 of FIG. 2A is a bowl-shaped recess which extendssymmetrically circumferentially about and within face 15 a curved depth14 created by curved edge 4 as flying knife 2 rotates perpendicularlywith respect to the direction along which a length of extrudate to becross-sectioned into inventive preform 16 progresses.

In contrast, preform 19 has an almost level face 17. In this regard,conventional flying knife 3 can produce a face 17 that is substantiallylevel but may not be completely level even though flying knife 3 has astraight edge due to forces acting on the extrudate as the extrudateprogresses along a plane that is perpendicular to rotatably strikingstraight edge flying knife 3.

Inventive preform 16 of FIG. 2A has a posterior end 20 that opposesinward curved depth 14 and thereby extends outwardly from preform 16 anoutward depth 21. In contrast, conventional preform 19 of FIG. 2B has aposterior end 22 that opposes face 17 and is substantially level but maynot be completely level and may extend slightly outward from preform 19.

Preforms 16 may each then be deposited/placed in golf ball componentmolds (not shown) such that curved faces 15 are positioned face up ineach golf ball component mold, whereas posterior ends 20 are adjacent toand do contact and are adjacent the golf ball component mold. Once thegolf ball component mold containing a preform is loaded into a moldpress, the press is closed, and sufficient heat and pressure is applied,each preform face 15 is converted into a half shell having a uniformlydistributed thickness about the half-shell and an inner surface contourwhich uniquely and suitably conforms with the contour of an outersurface of a spherically shaped subassembly—thereby producing betterconcentricity between the subassembly and outer layers once a pair ofhalf-shells are compression molded about the subassembly.

FIG. 1C is yet another example of an inventive curved flying knife ofthe invention. Curved flying knife 23 includes, among other commonelements introduced with respect to the curved flying knife of FIG. 1A,a curved edge 4 which curves away from opposing edge 11 and has an arch24 and rise 25 which are less than arch 12 and rise 13 the curved flyingknife of FIG. 1A. but nonetheless suitable for creating an inwardlycurved depth/bowl-shaped recess in a preform face and therefore ahalf-shell having a uniformly distributed thickness about the half-shelland an inner surface contour producing excellent concentricity between asubassembly and a pair of half-shells molded about the subassembly.

FIG. 3 depicts a suitable cutting location 26 in the process forcreating a plurality of preforms, wherein a length of extrudate proceedsin direction 28 for cross-sectioning while a curved flying knife such asthose of FIGS. 1A and/or 1C rotates in direction 29 between tubes 27Aand 27B, and perpendicularly with respect to direction 28 tocross-section the extrudate at predetermined intervals.

In alternative embodiments, the curved depth may be greater than thedepth by from about 5% to 20%, or from 5% to 20%, or from about 10% to20%, or from 10% to 20%, or from about 15% to 20%, or from 15% to 20%,or from about 5% to about 15%, or from 5% to 15%, or from about 5% toabout 10%, or from 5% to 10%, or from about 10% to about 15%, or from10% to 15%, or greater than 5%, or 10% or greater, or at least 15%, orabout 20%.

In particular embodiments, the rise of an inventive curved flying knifesuch as rise 13 or rise 24 can be as high as 1.0 inch (2.54 cm). Inother embodiments, the rise can be up to 0.75 inches (1.90 cm), or up to0.50 inches (1.27 cm). In some embodiments, the rise can be between 0.25inches (0.63 cm) and 1.0 inches, or from 0.25 inches to about 1.0inches, or from about 0.50 inches to about 1.0 inches, or from about0.50 inches to 0.75 inches, or from 0.50 inches to about 0.75 inches. Itis envisioned that the rise can be greater than 1.0 inches so long asresulting curved depth 14 in a preform of the invention displays andproduces improved half-shells of the invention having the improvementsand characteristics described herein.

In one non-limiting example, resulting preform 2 has a predeterminedinterval from outer edge 14 a of face 14 to outer edge 20 a of posteriorend 20 of about 2 cm. Curved depth 14 is about 4 mm inward from outeredge 14 a. In turn, outward depth 21 is about 4 mm outward from outeredge 20 a. In this embodiment, a preform 19, cross-sectioned with astraight-edge flying knife 3, has a face 17 with a depth 18 that is 20%less than curved depth 14. Depth 18 is measured from inward from oracross outer edge 17 a. In turn, any depth 21 is measured outward fromor across from edge 22 a.

Embodiments are indeed envisioned wherein curved flying knives 2 and/or23 are constructed so as to create a curved depth 14 of up to 50% of thedistance between outer edge 14 a and outer edge 20 a of preform 2 ofFIG. 2A. Rise 13 of curved flying knife 2 provides a unique andbowl-shaped recess and contour in curved depth 14 of preform face 15which more closely follows the ultimate contour of a molded half-shelland therefor improves moldability of the half-shell without creatingimperfections of deficiencies that would produce a non-centeredsubassembly when a pair of half-shells are compression molded about thesubassembly. This therefore contributes to a more uniform thicknessdistribution within and about resulting half-shells which in turn havebetter comformity with the subassembly about which a pair of half-shellsare compression molded.

Flying knives 2 and 23 can have a top view 30 of FIG. 4A which extendsfrom inner end 8 to distal end 9 of elongated body 11 and appearsstraight, with locations a, b, c and d of FIG. 4A corresponding tolocations a, b, c and d of each of FIGS. 1A and 1C.

Further, FIG. 4B depicts a top view 32 of two additional embodiments ofa flying knife of the invention, namely example flying knife 34 of FIG.5A and example flying knife 36 of FIG. 5B. In these embodiments, thecurved flying knife may comprise: (a) an elongated body defining aninner end and a distal end; the inner end being rotatably connectable toa device for cross-sectioning a length of extrudate into a plurality ofpreforms; and (b) a curved face located on the elongated body between abladed edge and an opposing edge; wherein each of the bladed edge andthe opposing edge co-extend from the distal end toward the inner end apredetermined length and follow the contour of the curved face; andwherein the curved face curves toward the extrudate while the bladededge cross-sections the extrudate. In this embodiment, the bladed edgemay be straight edged, or alternatively, have a curved edge that curvesaway from the opposing edge and contacts the extrudate andcross-sections it (such as curved edges 4 of inventive flying knives 2and 23).

Top view 32 of FIG. 4B extends from inner end 8 to distal end 9 ofelongated body 11, with locations a, b, c and d of FIG. 4A correspondingto locations a, b, c and d of each of FIGS. 5A and 5B. In each of flyingknife 34 and flying knife 36, elongated body 11 has a curved face 38between locations a and b rather than the straight face of inventiveflying knives 2 and 23 between locations a and b. And curved face 38 hasa curvature angle 40 of up to 20° with respect to a line betweenlocations a and b. Meanwhile, an opposing side 42 of curved face 38 isexposed to a length of extrudate during cross-sectioning.

Inventive flying knife 36 of FIG. 5B differs from inventive flying knife34 of FIG. 5A in that inventive flying knife 36 has a curved edge 4,whereas flying knife 34 has a straight edge 5, each therefore creatingquite different and unique curved depths 14 in an inventive preform 16even though both flying knife 34 and flying knife 36 have a curved face38 and opposing side 42.

The invention also relates to a golf ball comprising a sphericalsubassembly surrounded by an outer layer comprised of first and secondcompression molded half-shells comprised of preforms created bycross-sectioning a length of rubber extrudate at predetermined intervalsusing a curved edge flying knife and have first and secondcross-sectioned surfaces each which curve inward toward a posterior endof the preform and have a curved depth that is greater than a depthcreated by a straight edge flying knife.

In one embodiment, the subassembly is a rubber inner core and the outerlayer is a rubber outer core layer. In one such embodiment, the rubberof the inner core and the rubber of the outer core layer differ.

Typically, a Banbury-type mixer or the like is used to mix thepolybutadiene rubber composition. The rubber composition is extruded asan extrudate and cut to a predetermined shape, such as a cylinder,typically called a “preform”. The preform comprising the uncuredpolybutadiene composition

The invention further relates to a curved flying knife having: (a) anelongated body defining an inner end and a distal end; wherein the innerend is rotatably connectable to a device for creating a plurality ofpreforms from at least one length of extrudate; (b) a curved edgelocated on a first side of the elongated body and an opposing edgelocated on the opposite side of the elongated body; wherein each of thecurved edge and the opposing edge extend between the inner end anddistal end; and wherein the curved edge curves away from the opposingedge at least at a at a location on the first side that contacts theextrudate and cross-sections it and to a degree sufficient to create across-sectioned surface in each preform of extrudate that curves inwardtoward a posterior end of the preform and has a curved depth that isgreater than a depth created by a straight edge flying knife. In aparticular embodiment, the curved depth is greater than the depth by upto 20%.

Embodiments are also envisioned wherein first and second inventivepreforms are created as describe above but are molded directly about asubassembly using molding processes known in the art rather than beingpre-molded into half shells.

It was counterintuitive to try the inventive curved-blade flying knifewhen cross-sectioning extrudate into preforms because increasing thevolume of the blade contacting the extrudate also increases engagementtime between blade and extrudate which has been known to negativelyimpact cur quality and increase overall manufacture time and therebycosts. Unexpectedly, increasing the engagement time using a curvedflying knife blade improves the quality and shape of the preform used toform a half-shell which in turn improves concentricity betweensubassembly and resulting pair of compression molded half-shells.

Golf balls having various constructions may be made in accordance withthis invention, as long as at least one improved outer layer iscompression molded about at least one inner layer and formed from animproved half-shell that is comprised of a preform of the invention andformed using the methods and curved flying knife as described herein.Thus, golf balls of the invention may have at least two layers (twopiece), and may alternatively be three piece, four-piece, andfive-piece, etc. constructions with single or multi-layered cores,intermediate layers, and/or covers.

As used herein the term, “layer” means generally any spherical portionof the golf ball. More particularly, in one version, a two-piece golfball containing a core surrounded by a compression molded cover is made.Three-piece golf balls may be made containing a dual-layered core andsingle-layered cover, wherein at least one of an outer core layer andthe cover are compression molded according to the golf ball componentsand methods of the invention. In another version, a four-piece golf ballcontaining a dual-core and dual-cover (inner cover and outer coverlayers) is made, wherein any one or more of the outer layers iscompression molded according to the invention.

As used herein, the term, “intermediate layer” refers to any layer ofthe ball disposed between the innermost spherical core and the outermostcover layer and may include outer core layers, casing/mantle layers andinner cover layers. The diameter and thickness of the different layersalong with properties such as hardness and compression may varydepending upon the construction and desired playing performanceproperties of the golf ball as discussed further below. And acompression molded layer of a golf ball of the invention may have anyknown compression moldable thickness.

In a particular embodiment, an outer core layer of compression moldedinventive half-shells comprised of inventive preform comprises a rubbercomposition (polybutadiene rubber material) and is compression moldedabout an inner core that comprises a different rubber material.

It is envisioned that a compression molded layer of the invention mayinclude any compression moldable composition or material.

In an embodiment wherein the inner core and outer core layer comprise adifferent rubber materials, such may be selected, for example, frompolybutadiene, ethylene-propylene rubber, ethylene-propylene-dienerubber, polyisoprene, styrene-butadiene rubber, polyalkenamers, butylrubber, halobutyl rubber, or polystyrene elastomers.

In general, polybutadiene is a homopolymer of 1,3-butadiene. The doublebonds in the 1,3-butadiene monomer are attacked by catalysts to grow thepolymer chain and form a polybutadiene polymer having a desiredmolecular weight. Any suitable catalyst may be used to synthesize thepolybutadiene rubber depending upon the desired properties. Normally, atransition metal complex (for example, neodymium, nickel, or cobalt) oran alkyl metal such as alkyllithium is used as a catalyst. Othercatalysts include, but are not limited to, aluminum, boron, lithium,titanium, and combinations thereof. The catalysts produce polybutadienerubbers having different chemical structures. In a cis-bondconfiguration, the main internal polymer chain of the polybutadieneappears on the same side of the carbon-carbon double bond contained inthe polybutadiene. In a trans-bond configuration, the main internalpolymer chain is on opposite sides of the internal carbon-carbon doublebond in the polybutadiene. The polybutadiene rubber can have variouscombinations of cis- and trans-bond structures. A preferredpolybutadiene rubber has a 1,4 cis-bond content of at least 40%,preferably greater than 80%, and more preferably greater than 90%. Ingeneral, polybutadiene rubbers having a high 1,4 cis-bond content havehigh tensile strength. The polybutadiene rubber may have a relativelyhigh or low Mooney viscosity.

Examples of commercially-available polybutadiene rubbers that can beused in accordance with this invention, include, but are not limited to,BR 01 and BR 1220, available from BST Elastomers of Bangkok, Thailand;SE BR 1220LA and SE BR1203, available from DOW Chemical Co of Midland,Mich.; BUDENE 1207, 1207s, 1208, and 1280 available from Goodyear, Incof Akron, Ohio; BR 01, 51 and 730, available from Japan Synthetic Rubber(JSR) of Tokyo, Japan; BUNA CB 21, CB 22, CB 23, CB 24, CB 25, CB 29MES, CB 60, CB Nd 60, CB 55 NF, CB 70 B, CB KA 8967, and CB 1221,available from Lanxess Corp. of Pittsburgh. Pa.; BR1208, available fromLG Chemical of Seoul, South Korea; UBEPOL BR130B, BR150, BR150B, BR150L,BR230, BR360L, BR710, and VCR617, available from UBE Industries, Ltd. ofTokyo, Japan; EUROPRENE NEOCIS BR 60, INTENE 60 AF and P30AF, andEUROPRENE BR HV80, available from Polimeri Europa of Rome, Italy; AFDENE50 and NEODENE BR40, BR45, BR50 and BR60, available from Karbochem (PTY)Ltd. of Bruma, South Africa; KBR 01, NdBr 40, NdBR-45, NdBr 60, KBR710S, KBR 710H, and KBR 750, available from Kumho Petrochemical Co.,Ltd. Of Seoul, South Korea; and DIENE 55NF, 70AC, and 320 AC, availablefrom Firestone Polymers of Akron, Ohio.

To form the core, the polybutadiene rubber is used in an amount of atleast about 5% by weight based on total weight of composition and isgenerally present in an amount of about 5% to about 100%, or an amountwithin a range having a lower limit of 5% or 10% or 20% or 30% or 40% or50% and an upper limit of 55% or 60% or 70% or 80% or 90% or 95% or100%. In general, the concentration of polybutadiene rubber is about 45to about 95 weight percent. Preferably, the rubber material used to formthe core layer comprises at least 50% by weight, and more preferably atleast 70% by weight, polybutadiene rubber.

The rubber compositions of this invention may be cured, either bypre-blending or post-blending, using conventional curing processes.Suitable curing processes include, for example, peroxide-curing,sulfur-curing, high-energy radiation, and combinations thereof.Preferably, the rubber composition contains a free-radical initiatorselected from organic peroxides, high energy radiation sources capableof generating free-radicals, and combinations thereof. In one preferredversion, the rubber composition is peroxide-cured. Suitable organicperoxides include, but are not limited to, dicumyl peroxide;n-butyl-4,4-di(t-butylperoxy) valerate;1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane;2,5-dimethyl-2,5-di(t-butylperoxy) hexane; di-t-butyl peroxide;di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide;2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3;di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoylperoxide; t-butyl hydroperoxide; and combinations thereof. In aparticular embodiment, the free radical initiator is dicumyl peroxide,including, but not limited to Perkadox® BC, commercially available fromAkzo Nobel. Peroxide free-radical initiators are generally present inthe rubber composition in an amount of at least 0.05 parts by weight per100 parts of the total rubber, or an amount within the range having alower limit of 0.05 parts or 0.1 parts or 1 part or 1.25 parts or 1.5parts or 2.5 parts or 5 parts by weight per 100 parts of the totalrubbers, and an upper limit of 2.5 parts or 3 parts or 5 parts or 6parts or 10 parts or 15 parts by weight per 100 parts of the totalrubber. Concentrations are in parts per hundred (phr) unless otherwiseindicated. As used herein, the term, “parts per hundred,” also known as“phr” or “pph” is defined as the number of parts by weight of aparticular component present in a mixture, relative to 100 parts byweight of the polymer component. Mathematically, this can be expressedas the weight of an ingredient divided by the total weight of thepolymer, multiplied by a factor of 100.

The rubber compositions preferably include a reactive cross-linkingco-agent. Suitable co-agents include, but are not limited to, metalsalts of unsaturated carboxylic acids having from 3 to 8 carbon atoms;unsaturated vinyl compounds and polyfunctional monomers (e.g.,trimethylolpropane trimethacrylate); phenylene bismaleimide; andcombinations thereof. Particular examples of suitable metal saltsinclude, but are not limited to, one or more metal salts of acrylates,diacrylates, methacrylates, and dimethacrylates, wherein the metal isselected from magnesium, calcium, zinc, aluminum, lithium, and nickel.In a particular embodiment, the co-agent is selected from zinc salts ofacrylates, diacrylates, methacrylates, and dimethacrylates. In anotherparticular embodiment, the agent is zinc diacrylate (ZDA). When theco-agent is zinc diacrylate and/or zinc dimethacrylate, the co-agent istypically included in the rubber composition in an amount within therange having a lower limit of 1 or 5 or 10 or 15 or 19 or 20 parts byweight per 100 parts of the total rubber, and an upper limit of 24 or 25or 30 or 35 or 40 or 45 or 50 or 60 parts by weight per 100 parts of thebase rubber.

Radical scavengers such as a halogenated organosulfur or metal saltthereof, organic disulfide, or inorganic disulfide compounds may beadded to the rubber composition. These compounds also may function as“soft and fast agents.” As used herein, “soft and fast agent” means anycompound or a blend thereof that is capable of making a core: 1) softer(having a lower compression) at a constant “coefficient of restitution”(COR); and/or 2) faster (having a higher COR at equal compression), whencompared to a core equivalently prepared without a soft and fast agent.Preferred halogenated organosulfur compounds include, but are notlimited to, pentachlorothiophenol (PCTP) and salts of PCTP such as zincpentachlorothiophenol (ZnPCTP). Using PCTP and ZnPCTP in golf ball innercores helps produce softer and faster inner cores. The PCTP and ZnPCTPcompounds help increase the resiliency and the coefficient ofrestitution of the core. In a particular embodiment, the soft and fastagent is selected from ZnPCTP, PCTP, ditolyl disulfide, diphenyldisulfide, dixylyl disulfide, 2-nitroresorcinol, and combinationsthereof.

The rubber compositions of the present invention also may include“fillers,” which are added to adjust the density and/or specific gravityof the material. Suitable fillers include, but are not limited to,polymeric or mineral fillers, metal fillers, metal alloy fillers, metaloxide fillers and carbonaceous fillers. The fillers can be in anysuitable form including, but not limited to, flakes, fibers, whiskers,fibrils, plates, particles, and powders. Rubber regrind, which isground, recycled rubber material (for example, ground to about 30 meshparticle size) obtained from discarded rubber golf ball cores, also canbe used as a filler. The amount and type of fillers utilized aregoverned by the amount and weight of other ingredients in the golf ball,since a maximum golf ball weight of 45.93 g (1.62 ounces) has beenestablished by the United States Golf Association (USGA).

Suitable polymeric or mineral fillers that may be added to the rubbercomposition include, for example, precipitated hydrated silica, clay,talc, asbestos, glass fibers, aramid fibers, mica, calcium metasilicate,barium sulfate, zinc sulfide, lithopone, silicates, silicon carbide,tungsten carbide, diatomaceous earth, polyvinyl chloride, carbonatessuch as calcium carbonate and magnesium carbonate. Suitable metalfillers include titanium, tungsten, aluminum, bismuth, nickel,molybdenum, iron, lead, copper, boron, cobalt, beryllium, zinc, and tin.Suitable metal alloys include steel, brass, bronze, boron carbidewhiskers, and tungsten carbide whiskers. Suitable metal oxide fillersinclude zinc oxide, iron oxide, aluminum oxide, titanium oxide,magnesium oxide, and zirconium oxide. Suitable particulate carbonaceousfillers include graphite, carbon black, cotton flock, natural bitumen,cellulose flock, and leather fiber. Micro balloon fillers such as glassand ceramic, and fly ash fillers can also be used. In a particularaspect of this embodiment, the rubber composition includes filler(s)selected from carbon black, nanoclays (e.g., Cloisite® and Nanofil®nanoclays, commercially available from Southern Clay Products, Inc., andNanomax® and Nanomer® nanoclays, commercially available from Nanocor,Inc.), talc (e.g., Luzenac HAR® high aspect ratio talcs, commerciallyavailable from Luzenac America, Inc.), glass (e.g., glass flake, milledglass, and microglass), mica and mica-based pigments (e.g., Iriodin®pearl luster pigments, commercially available from The Merck Group), andcombinations thereof. In a particular embodiment, the rubber compositionis modified with organic fiber micropulp.

In addition, the rubber compositions may include antioxidants to preventthe breakdown of the elastomers. Also, processing aids such as highmolecular weight organic acids and salts thereof, may be added to thecomposition. In a particular embodiment, the total amount of additive(s)and filler(s) present in the rubber composition is 15 wt % or less, or12 wt % or less, or 10 wt % or less, or 9 wt % or less, or 6 wt % orless, or 5 wt % or less, or 4 wt % or less, or 3 wt % or less, based onthe total weight of the rubber composition.

The polybutadiene rubber material (base rubber) may be blended withother elastomers in accordance with this invention. Other elastomersinclude, but are not limited to, polybutadiene, polyisoprene, ethylenepropylene rubber (“EPR”), styrene-butadiene rubber, styrenic blockcopolymer rubbers (such as “SI”, “SIS”, “SB”, “SBS”, “SIBS”, and thelike, where “S” is styrene, “I” is isobutylene, and “B” is butadiene),polyalkenamers such as, for example, polyoctenamer, butyl rubber,halobutyl rubber, polystyrene elastomers, polyethylene elastomers,polyurethane elastomers, polyurea elastomers, metallocene-catalyzedelastomers and plastomers, copolymers of isobutylene and p-alkylstyrene,halogenated copolymers of isobutylene and p-alkylstyrene, copolymers ofbutadiene with acrylonitrile, polychloroprene, alkyl acrylate rubber,chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber,and combinations of two or more thereof.

The polymers, free-radical initiators, filler, cross-linking agents, andany other materials used in forming either the golf ball center or anyof the core, in accordance with invention, may be combined to form amixture by any type of mixing known to one of ordinary skill in the art.Suitable types of mixing include single pass and multi-pass mixing, andthe like. The cross-linking agent, and any other optional additives usedto modify the characteristics of the golf ball center or additionallayer(s), may similarly be combined by any type of mixing. A single-passmixing process where ingredients are added sequentially is preferred, asthis type of mixing tends to increase efficiency and reduce costs forthe process. The preferred mixing cycle is single step wherein thepolymer, cis-to-trans catalyst, filler, zinc diacrylate, and peroxideare added in sequence.

In one preferred embodiment, the entire core or at least one core layerin a multi-layered structure is formed of a rubber compositioncomprising a material selected from the group of natural and syntheticrubbers including, but not limited to, polybutadiene, polyisoprene,ethylene propylene rubber (“EPR”), ethylene-propylene-diene (“EPDM”)rubber, styrene-butadiene rubber, styrenic block copolymer rubbers (suchas “SI”, “SIS”, “SB”, “SBS”, “SIBS”, and the like, where “S” is styrene,“I” is isobutylene, and “B” is butadiene), polyalkenamers such as, forexample, polyoctenamer, butyl rubber, halobutyl rubber, polystyreneelastomers, polyethylene elastomers, polyurethane elastomers, polyureaelastomers, metallocene-catalyzed elastomers and plastomers, copolymersof isobutylene and p-alkylstyrene, halogenated copolymers of isobutyleneand p-alkylstyrene, copolymers of butadiene with acrylonitrile,polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber,acrylonitrile chlorinated isoprene rubber, and combinations of two ormore thereof.

Golf ball layers can be formed from any materials known in the art,including thermoplastic and thermosetting materials. For example,suitable materials include ionomer compositions comprising an ethyleneacid copolymer containing acid groups that are at least partiallyneutralized. Suitable ethylene acid copolymers that may be used to formthe intermediate layers are generally referred to as copolymers ofethylene; C₃ to C₈ α, β-ethylenically unsaturated mono- or dicarboxylicacid; and optional softening monomer. These ethylene acid copolymerionomers also can be used to form the inner core and outer core layersas described above.

Suitable ionomer compositions include partially-neutralized ionomers andhighly-neutralized ionomers (HNPs), including ionomers formed fromblends of two or more partially-neutralized ionomers, blends of two ormore highly-neutralized ionomers, and blends of one or morepartially-neutralized ionomers with one or more highly-neutralizedionomers. For purposes of the present disclosure, “HNP” refers to anacid copolymer after at least 70% of all acid groups present in thecomposition are neutralized. Preferred ionomers are salts of O/X- andO/X/Y-type acid copolymers, wherein O is an α-olefin, X is a C₃-C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningmonomer. 0 is preferably selected from ethylene and propylene. X ispreferably selected from methacrylic acid, acrylic acid, ethacrylicacid, crotonic acid, and itaconic acid. Methacrylic acid and acrylicacid are particularly preferred. Y is preferably selected from (meth)acrylate and alkyl (meth) acrylates wherein the alkyl groups have from 1to 8 carbon atoms, including, but not limited to, n-butyl (meth)acrylate, isobutyl (meth) acrylate, methyl (meth) acrylate, and ethyl(meth) acrylate.

Preferred O/X and O/X/Y-type copolymers include, without limitation,ethylene acid copolymers, such as ethylene/(meth)acrylic acid,ethylene/(meth)acrylic acid/maleic anhydride, ethylene/(meth)acrylicacid/maleic acid mono-ester, ethylene/maleic acid, ethylene/maleic acidmono-ester, ethylene/(meth)acrylic acid/n-butyl (meth)acrylate,ethylene/(meth)acrylic acid/iso-butyl (meth)acrylate,ethylene/(meth)acrylic acid/methyl (meth)acrylate,ethylene/(meth)acrylic acid/ethyl (meth)acrylate terpolymers, and thelike. The term, “copolymer,” as used herein, includes polymers havingtwo types of monomers, those having three types of monomers, and thosehaving more than three types of monomers. Preferred α, β-ethylenicallyunsaturated mono- or dicarboxylic acids are (meth) acrylic acid,ethacrylic acid, maleic acid, crotonic acid, fumaric acid, itaconicacid. (Meth) acrylic acid is most preferred. As used herein, “(meth)acrylic acid” means methacrylic acid and/or acrylic acid. Likewise,“(meth) acrylate” means methacrylate and/or acrylate.

In a particularly preferred version, highly neutralized E/X- andE/X/Y-type acid copolymers, wherein E is ethylene, X is a C₃-C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningmonomer are used. X is preferably selected from methacrylic acid,acrylic acid, ethacrylic acid, crotonic acid, and itaconic acid.Methacrylic acid and acrylic acid are particularly preferred. Y ispreferably an acrylate selected from alkyl acrylates and aryl acrylatesand preferably selected from (meth) acrylate and alkyl (meth) acrylateswherein the alkyl groups have from 1 to 8 carbon atoms, including, butnot limited to, n-butyl (meth) acrylate, isobutyl (meth) acrylate,methyl (meth) acrylate, and ethyl (meth) acrylate. Preferred E/X/Y-typecopolymers are those wherein X is (meth) acrylic acid and/or Y isselected from (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth)acrylate, methyl (meth) acrylate, and ethyl (meth) acrylate. Morepreferred E/X/Y-type copolymers are ethylene/(meth) acrylic acid/n-butylacrylate, ethylene/(meth) acrylic acid/methyl acrylate, andethylene/(meth) acrylic acid/ethyl acrylate.

The amount of ethylene in the acid copolymer is typically at least 15wt. %, preferably at least 25 wt. %, more preferably least 40 wt. %, andeven more preferably at least 60 wt. %, based on total weight of thecopolymer. The amount of C₃ to C₈ α, β-ethylenically unsaturated mono-or dicarboxylic acid in the acid copolymer is typically from 1 wt. % to35 wt. %, preferably from 5 wt. % to 30 wt. %, more preferably from 5wt. % to 25 wt. %, and even more preferably from 10 wt. % to 20 wt. %,based on total weight of the copolymer. The amount of optional softeningcomonomer in the acid copolymer is typically from 0 wt. % to 50 wt. %,preferably from 5 wt. % to 40 wt. %, more preferably from 10 wt. % to 35wt. %, and even more preferably from 20 wt. % to 30 wt. %, based ontotal weight of the copolymer. “Low acid” and “high acid” ionomericpolymers, as well as blends of such ionomers, may be used. In general,low acid ionomers are considered to be those containing 16 wt. % or lessof acid moieties, whereas high acid ionomers are considered to be thosecontaining greater than 16 wt. % of acid moieties.

The various O/X, E/X, O/X/Y, and E/X/Y-type copolymers are at leastpartially neutralized with a cation source, optionally in the presenceof a high molecular weight organic acid, such as those disclosed in U.S.Pat. No. 6,756,436, the entire disclosure of which is herebyincorporated herein by reference. The acid copolymer can be reacted withthe optional high molecular weight organic acid and the cation sourcesimultaneously, or prior to the addition of the cation source. Suitablecation sources include, but are not limited to, metal ion sources, suchas compounds of alkali metals, alkaline earth metals, transition metals,and rare earth elements; ammonium salts and monoamine salts; andcombinations thereof. Preferred cation sources are compounds ofmagnesium, sodium, potassium, cesium, calcium, barium, manganese,copper, zinc, lead, tin, aluminum, nickel, chromium, lithium, and rareearth metals.

Other suitable thermoplastic polymers that may be used to form golf balllayers include, but are not limited to, the following polymers(including homopolymers, copolymers, and derivatives thereof: (a)polyester, particularly those modified with a compatibilizing group suchas sulfonate or phosphonate, including modified poly(ethyleneterephthalate), modified poly(butylene terephthalate), modifiedpoly(propylene terephthalate), modified poly(trimethyleneterephthalate), modified poly(ethylene naphthenate), and those disclosedin U.S. Pat. Nos. 6,353,050, 6,274,298, and 6,001,930, the entiredisclosures of which are hereby incorporated herein by reference, andblends of two or more thereof; (b) polyamides, polyamide-ethers, andpolyamide-esters, and those disclosed in U.S. Pat. Nos. 6,187,864,6,001,930, and 5,981,654, the entire disclosures of which are herebyincorporated herein by reference, and blends of two or more thereof; (c)polyurethanes, polyureas, polyurethane-polyurea hybrids, and blends oftwo or more thereof; (d) fluoropolymers, such as those disclosed in U.S.Pat. Nos. 5,691,066, 6,747,110 and 7,009,002, the entire disclosures ofwhich are hereby incorporated herein by reference, and blends of two ormore thereof; (e) polystyrenes, such as poly(styrene-co-maleicanhydride), acrylonitrile-butadiene-styrene, poly(styrene sulfonate),polyethylene styrene, and blends of two or more thereof; (f) polyvinylchlorides and grafted polyvinyl chlorides, and blends of two or morethereof; (g) polycarbonates, blends ofpolycarbonate/acrylonitrile-butadiene-styrene, blends ofpolycarbonate/polyurethane, blends of polycarbonate/polyester, andblends of two or more thereof; (h) polyethers, such as polyaryleneethers, polyphenylene oxides, block copolymers of alkenyl aromatics withvinyl aromatics and polyamicesters, and blends of two or more thereof;(i) polyimides, polyetherketones, polyamideimides, and blends of two ormore thereof; and (j) polycarbonate/polyester copolymers and blends.

It also is recognized that thermoplastic materials can be “converted”into thermoset materials by cross-linking the polymer chains so theyform a network structure, and such cross-linked thermoplastic materialsmay be used to form the core and intermediate layers in accordance withthis invention. For example, thermoplastic polyolefins such as linearlow density polyethylene (LLDPE), low density polyethylene (LDPE), andhigh density polyethylene (HDPE) may be cross-linked to form bondsbetween the polymer chains. The cross-linked thermoplastic materialtypically has improved physical properties and strength overnon-cross-linked thermoplastics, particularly at temperatures above thecrystalline melting point. Preferably a partially or fully-neutralizedionomer, as described above, is covalently cross-linked to render itinto a thermoset composition (that is, it contains at least some levelof covalent, irreversable cross-links). Thermoplastic polyurethanes andpolyureas also may be converted into thermoset materials in accordancewith the present invention.

The cross-linked thermoplastic material may be created by exposing thethermoplastic to: 1) a high-energy radiation treatment, such as electronbeam or gamma radiation, such as disclosed in U.S. Pat. No. 5,891,973,which is incorporated by reference herein, 2) lower energy radiation,such as ultra-violet (UV) or infra-red (IR) radiation; 3) a solutiontreatment, such as an isocyanate or a silane; 4) incorporation ofadditional free radical initiator groups in the thermoplastic prior tomolding; and/or 5) chemical modification, such as esterification orsaponification, to name a few.

Modifications in thermoplastic polymeric structure can be induced by anumber of methods, including exposing the thermoplastic material tohigh-energy radiation or through a chemical process using peroxide.Radiation sources include, but are not limited to, gamma-rays,electrons, neutrons, protons, x-rays, helium nuclei, or the like. Gammaradiation, typically using radioactive cobalt atoms and allows forconsiderable depth of treatment, if necessary. For core layers requiringlower depth of penetration, electron-beam accelerators or UV and IRlight sources can be used. Useful UV and IR irradiation methods aredisclosed in U.S. Pat. Nos. 6,855,070 and 7,198,576, which areincorporated herein by reference. The thermoplastic layers may beirradiated at dosages greater than 0.05 Mrd, or ranging from 1 Mrd to 20Mrd, or ranging from 2 Mrd to 15 Mrd, or ranging from 4 Mrd to 10 Mrd.In one embodiment, the layer may be irradiated at a dosage from 5 Mrd to8 Mrd and in another embodiment, the layer may be irradiated with adosage from 0.05 Mrd to 3 Mrd, or from 0.05 Mrd to 1.5 Mrd.

It is meanwhile envisioned that in some embodiments/golf ballconstructions, it may be beneficial to also include at least one layerformed from or blended with a conventional isocyante-based material. Thefollowing conventional compositions as known in the art may beincorporated to achieve particular desired golf ball characteristics:

(1) Polyurethanes, such as those prepared from polyols and diisocyanatesor polyisocyanates and/or their prepolymers, and those disclosed in U.S.Pat. Nos. 5,334,673 and 6,506,851;

(2) Polyureas, such as those disclosed in U.S. Pat. Nos. 5,484,870 and6,835,794; and

(3) Polyurethane/urea hybrids, blends or copolymers comprising urethaneand urea segments such as those disclosed in U.S. Pat. No. 8,506,424.

Suitable polyurethane compositions comprise a reaction product of atleast one polyisocyanate and at least one curing agent. The curing agentcan include, for example, one or more polyols. The polyisocyanate can becombined with one or more polyols to form a prepolymer, which is thencombined with the at least one curing agent. Thus, the polyols describedherein are suitable for use in one or both components of thepolyurethane material, i.e., as part of a prepolymer and in the curingagent. Suitable polyurethanes are described in U.S. Pat. No. 7,331,878,which is incorporated herein in its entirety by reference.

In general, polyurea compositions contain urea linkages formed byreacting an isocyanate group (—N═C═O) with an amine group (NH or NH₂).The chain length of the polyurea prepolymer is extended by reacting theprepolymer with an amine curing agent. The resulting polyurea haselastomeric properties, because of its “hard” and “soft” segments, whichare covalently bonded together. The soft, amorphous, low-melting pointsegments, which are formed from the polyamines, are relatively flexibleand mobile, while the hard, high-melting point segments, which areformed from the isocyanate and chain extenders, are relatively stiff andimmobile. The phase separation of the hard and soft segments providesthe polyurea with its elastomeric resiliency. The polyurea compositioncontains urea linkages having the following general structure:

where x is the chain length, i.e., about 1 or greater, and R and R₁ arestraight chain or branched hydrocarbon chains having about 1 to about 20carbon atoms.

A polyurea/polyurethane hybrid composition is produced when the polyureaprepolymer (as described above) is chain-extended using ahydroxyl-terminated curing agent. Any excess isocyanate groups in theprepolymer will react with the hydroxyl groups in the curing agent andcreate urethane linkages. That is, a polyurea/polyurethane hybridcomposition is produced.

In a preferred embodiment, a pure polyurea composition, as describedabove, is prepared. That is, the composition contains only urealinkages. An amine-terminated curing agent is used in the reaction toproduce the pure polyurea composition. However, it should be understoodthat a polyurea/polyurethane hybrid composition also may be prepared inaccordance with this invention as discussed above. Such a hybridcomposition can be formed if the polyurea prepolymer is cured with ahydroxyl-terminated curing agent. Any excess isocyanate in the polyureaprepolymer reacts with the hydroxyl groups in the curing agent and formsurethane linkages. The resulting polyurea/polyurethane hybridcomposition contains both urea and urethane linkages. The generalstructure of a urethane linkage is shown below:

where x is the chain length, i.e., about 1 or greater, and R and R₁ arestraight chain or branched hydrocarbon chains having about 1 to about 20carbon atoms.

There are two basic techniques that can be used to make the polyurea andpolyurea/urethane compositions of this invention: a) one-shot technique,and b) prepolymer technique. In the one-shot technique, the isocyanateblend, polyamine, and hydroxyl and/or amine-terminated curing agent arereacted in one step. On the other hand, the prepolymer techniqueinvolves a first reaction between the isocyanate blend and polyamine toproduce a polyurea prepolymer, and a subsequent reaction between theprepolymer and hydroxyl and/or amine-terminated curing agent. As aresult of the reaction between the isocyanate and polyamine compounds,there will be some unreacted NCO groups in the polyurea prepolymer. Theprepolymer should have less than 14% unreacted NCO groups. Preferably,the prepolymer has no greater than 8.5% unreacted NCO groups, morepreferably from 2.5% to 8%, and most preferably from 5.0% to 8.0%unreacted NCO groups. As the weight percent of unreacted isocyanategroups increases, the hardness of the composition also generallyincreases.

Either the one-shot or prepolymer method may be employed to produce thepolyurea and polyurea/urethane compositions of the invention; however,the prepolymer technique is preferred because it provides better controlof the chemical reaction. The prepolymer method provides a morehomogeneous mixture resulting in a more consistent polymer composition.The one-shot method results in a mixture that is inhomogeneous (morerandom) and affords the manufacturer less control over the molecularstructure of the resultant composition.

In the casting process, the polyurea and polyurea/urethane compositionscan be formed by chain-extending the polyurea prepolymer with a singlecuring agent or blend of curing agents as described further below. Thecompositions of the present invention may be selected from among bothcastable thermoplastic and thermoset materials. Thermoplastic polyureacompositions are typically formed by reacting the isocyanate blend andpolyamines at a 1:1 stoichiometric ratio. Thermoset compositions, on theother hand, are cross-linked polymers and are typically produced fromthe reaction of the isocyanate blend and polyamines at normally a 1.05:1stoichiometric ratio. In general, thermoset polyurea compositions areeasier to prepare than thermoplastic polyureas.

The polyurea prepolymer can be chain-extended by reacting it with asingle curing agent or blend of curing agents (chain-extenders). Ingeneral, the prepolymer can be reacted with hydroxyl-terminated curingagents, amine-terminated curing agents, or mixtures thereof. The curingagents extend the chain length of the prepolymer and build-up itsmolecular weight. Normally, the prepolymer and curing agent are mixed sothe isocyanate groups and hydroxyl or amine groups are mixed at a1.05:1.00 stoichiometric ratio.

A catalyst may be employed to promote the reaction between theisocyanate and polyamine compounds for producing the prepolymer orbetween prepolymer and curing agent during the chain-extending step.Preferably, the catalyst is added to the reactants before producing theprepolymer. Suitable catalysts include, but are not limited to, bismuthcatalyst; zinc octoate; stannous octoate; tin catalysts such asbis-butyltin dilaurate, bis-butyltin diacetate, stannous octoate; tin(II) chloride, tin (IV) chloride, bis-butyltin dimethoxide,dimethyl-bis[1-oxonedecyl)oxy]stannane, di-n-octyltin bis-isooctylmercaptoacetate; amine catalysts such as triethylenediamine,triethylamine, and tributylamine; organic acids such as oleic acid andacetic acid; delayed catalysts; and mixtures thereof. The catalyst ispreferably added in an amount sufficient to catalyze the reaction of thecomponents in the reactive mixture. In one embodiment, the catalyst ispresent in an amount from about 0.001 percent to about 1 percent, andpreferably 0.1 to 0.5 percent, by weight of the composition.

The hydroxyl chain-extending (curing) agents are preferably selectedfrom the group consisting of ethylene glycol; diethylene glycol;polyethylene glycol; propylene glycol; 2-methyl-1,3-propanediol;2-methyl-1,4-butanediol; monoethanolamine; diethanolamine;triethanolamine; monoisopropanolamine; diisopropanolamine; dipropyleneglycol; polypropylene glycol; 1,2-butanediol; 1,3-butanediol;1,4-butanediol; 2,3-butanediol; 2,3-dimethyl-2,3-butanediol;trimethylolpropane; cyclohexyldimethylol; triisopropanolamine;N,N,N′,N′-tetra-(2-hydroxypropyl)-ethylene diamine; diethylene glycolbis-(aminopropyl) ether; 1,5-pentanediol; 1,6-hexanediol;1,3-bis-(2-hydroxyethoxy) cyclohexane; 1,4-cyclohexyldimethylol;1,3-bis-[2-(2-hydroxyethoxy) ethoxy]cyclohexane;1,3-bis-{2-[2-(2-hydroxyethoxy) ethoxy]ethoxy}cyclohexane;trimethylolpropane; polytetramethylene ether glycol (PTMEG), preferablyhaving a molecular weight from about 250 to about 3900; and mixturesthereof.

Suitable amine chain-extending (curing) agents that can be used inchain-extending the polyurea prepolymer of this invention include, butare not limited to, unsaturated diamines such as4,4′-diamino-diphenylmethane (i.e., 4,4′-methylene-dianiline or “MDA”),m-phenylenediamine, p-phenylenediamine, 1,2- or1,4-bis(sec-butylamino)benzene, 3,5-diethyl-(2,4- or 2,6-)toluenediamine or “DETDA”, 3,5-dimethylthio-(2,4- or2,6-)toluenediamine, 3,5-diethylthio-(2,4- or 2,6-)toluenediamine,3,3′-dimethyl-4,4′-diamino-diphenylmethane,3,3′-diethyl-5,5′-dimethyl4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(2-ethyl-6-methyl-benezeneamine)),3,3′-dichloro-4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(2-chloroaniline) or “MOCA”),3,3′,5,5′-tetraethyl-4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(2,6-diethylaniline),2,2′-dichloro-3,3′,5,5′-tetraethyl-4,4′-diamino-diphenylmethane (i.e.,4,4′-methylene-bis(3-chloro-2,6-diethyleneaniline) or “MCDEA”),3,3′-diethyl-5,5′-dichloro-4,4′-diamino-diphenylmethane, or “MDEA”),3,3′-dichloro-2,2′,6,6′-tetraethyl-4,4′-diamino-diphenylmethane,3,3′-dichloro-4,4′-diamino-diphenylmethane,4,4′-methylene-bis(2,3-dichloroaniline) (i.e.,2,2′,3,3′-tetrachloro-4,4′-diamino-diphenylmethane or “MDCA”),4,4′-bis(sec-butylamino)-diphenylmethane,N,N′-dialkylamino-diphenylmethane,trimethyleneglycol-di(p-aminobenzoate),polyethyleneglycol-di(p-aminobenzoate),polytetramethyleneglycol-di(p-aminobenzoate); saturated diamines such asethylene diamine, 1,3-propylene diamine, 2-methyl-pentamethylenediamine, hexamethylene diamine, 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine, imino-bis(propylamine), imido-bis(propylamine),methylimino-bis(propylamine) (i.e.,N-(3-aminopropyl)-N-methyl-1,3-propanediamine),1,4-bis(3-aminopropoxy)butane (i.e.,3,3′-[1,4-butanediylbis-(oxy)bis]-1-propanamine),diethyleneglycol-bis(propylamine) (i.e.,diethyleneglycol-di(aminopropyl)ether),4,7,10-trioxatridecane-1,13-diamine, 1-methyl-2,6-diamino-cyclohexane,1,4-diamino-cyclohexane, poly(oxyethylene-oxypropylene) diamines, 1,3-or 1,4-bis(methylamino)-cyclohexane, isophorone diamine, 1,2- or1,4-bis(sec-butylamino)-cyclohexane, N,N′-diisopropyl-isophoronediamine, 4,4′-diamino-dicyclohexylmethane,3,3′-dimethyl-4,4′-diamino-dicyclohexylmethane,3,3′-dichloro-4,4′-diamino-dicyclohexylmethane,N,N′-dialkylamino-dicyclohexylmethane, polyoxyethylene diamines,3,3′-diethyl-5,5′-dimethyl-4,4′-diamino-dicyclohexylmethane,polyoxypropylene diamines,3,3′-diethyl-5,5′-dichloro-4,4′-diamino-dicyclohexylmethane,polytetramethylene ether diamines, 3,3′,5,5‘-tetraethyl-4,4’-diamino-dicyclohexylmethane (i.e.,4,4′-methylene-bis(2,6-diethylaminocyclohexane)),3,3′-dichloro-4,4′-diamino-dicyclohexylmethane,2,2′-dichloro-3,3′,5,5′-tetraethyl-4,4′-diamino-dicyclohexylmethane,(ethylene oxide)-capped polyoxypropylene ether diamines,2,2′,3,3′-tetrachloro-4,4′-diamino-dicyclohexylmethane,4,4′-bis(sec-butylamino)-dicyclohexylmethane; triamines such asdiethylene triamine, dipropylene triamine, (propylene oxide)-basedtriamines (i.e., polyoxypropylene triamines),N-(2-aminoethyl)-1,3-propylenediamine (i.e., N₃-amine), glycerin-basedtriamines, (all saturated); tetramines such asN,N′-bis(3-aminopropyl)ethylene diamine (i.e., N₄-amine) (bothsaturated), triethylene tetramine; and other polyamines such astetraethylene pentamine (also saturated). One suitable amine-terminatedchain-extending agent is Ethacure 300™ (dimethylthiotoluenediamine or amixture of 2,6-diamino-3,5-dimethylthiotoluene and2,4-diamino-3,5-dimethylthiotoluene.) The amine curing agents used aschain extenders normally have a cyclic structure and a low molecularweight (250 or less).

When the polyurea prepolymer is reacted with amine-terminated curingagents during the chain-extending step, as described above, theresulting composition is essentially a pure polyurea composition. On theother hand, when the polyurea prepolymer is reacted with ahydroxyl-terminated curing agent during the chain-extending step, anyexcess isocyanate groups in the prepolymer will react with the hydroxylgroups in the curing agent and create urethane linkages to form apolyurea/urethane hybrid.

This chain-extending step, which occurs when the polyurea prepolymer isreacted with hydroxyl curing agents, amine curing agents, or mixturesthereof, builds-up the molecular weight and extends the chain length ofthe prepolymer. When the polyurea prepolymer is reacted with aminecuring agents, a polyurea composition having urea linkages is produced.When the polyurea prepolymer is reacted with hydroxyl curing agents, apolyurea/urethane hybrid composition containing both urea and urethanelinkages is produced. The polyurea/urethane hybrid composition isdistinct from the pure polyurea composition. The concentration of ureaand urethane linkages in the hybrid composition may vary. In general,the hybrid composition may contain a mixture of about 10 to 90% urea andabout 90 to 10% urethane linkages. The resulting polyurea orpolyurea/urethane hybrid composition has elastomeric properties based onphase separation of the soft and hard segments. The soft segments, whichare formed from the polyamine reactants, are generally flexible andmobile, while the hard segments, which are formed from the isocyanatesand chain extenders, are generally stiff and immobile.

In an alternative embodiment, the cover layer may comprise aconventional polyurethane or polyurethane/urea hybrid composition. Ingeneral, polyurethane compositions contain urethane linkages formed byreacting an isocyanate group (—N═C═O) with a hydroxyl group (OH). Thepolyurethanes are produced by the reaction of a multi-functionalisocyanate (NCO—R—NCO) with a long-chain polyol having terminal hydroxylgroups (OH—OH) in the presence of a catalyst and other additives. Thechain length of the polyurethane prepolymer is extended by reacting itwith short-chain diols (OH—R′—OH). The resulting polyurethane haselastomeric properties because of its “hard” and “soft” segments, whichare covalently bonded together. This phase separation occurs because themainly non-polar, low melting soft segments are incompatible with thepolar, high melting hard segments. The hard segments, which are formedby the reaction of the diisocyanate and low molecular weightchain-extending diol, are relatively stiff and immobile. The softsegments, which are formed by the reaction of the diisocyanate and longchain diol, are relatively flexible and mobile. Because the hardsegments are covalently coupled to the soft segments, they inhibitplastic flow of the polymer chains, thus creating elastomericresiliency.

Suitable isocyanate compounds that can be used to prepare thepolyurethane or polyurethane/urea hybrid material are described above.These isocyanate compounds are able to react with the hydroxyl or aminecompounds and form a durable and tough polymer having a high meltingpoint. The resulting polyurethane generally has good mechanical strengthand cut/shear-resistance. In addition, the polyurethane composition hasgood light and thermal-stability.

When forming a polyurethane prepolymer, any suitable polyol may bereacted with the above-described isocyanate blends in accordance withthis invention. Exemplary polyols include, but are not limited to,polyether polyols, hydroxy-terminated polybutadiene (includingpartially/fully hydrogenated derivatives), polyester polyols,polycaprolactone polyols, and polycarbonate polyols. In one preferredembodiment, the polyol includes polyether polyol. Examples include, butare not limited to, polytetramethylene ether glycol (PTMEG),polyethylene propylene glycol, polyoxypropylene glycol, and mixturesthereof. The hydrocarbon chain can have saturated or unsaturated bondsand substituted or unsubstituted aromatic and cyclic groups. Preferably,the polyol of the present invention includes PTMEG.

In another embodiment, polyester polyols are included in thepolyurethane material. Suitable polyester polyols include, but are notlimited to, polyethylene adipate glycol; polybutylene adipate glycol;polyethylene propylene adipate glycol; o-phthalate-1,6-hexanediol;poly(hexamethylene adipate) glycol; and mixtures thereof. Thehydrocarbon chain can have saturated or unsaturated bonds, orsubstituted or unsubstituted aromatic and cyclic groups. In stillanother embodiment, polycaprolactone polyols are included in thematerials of the invention. Suitable polycaprolactone polyols include,but are not limited to: 1,6-hexanediol-initiated polycaprolactone,diethylene glycol initiated polycaprolactone, trimethylol propaneinitiated polycaprolactone, neopentyl glycol initiated polycaprolactone,1,4-butanediol-initiated polycaprolactone, and mixtures thereof. Thehydrocarbon chain can have saturated or unsaturated bonds, orsubstituted or unsubstituted aromatic and cyclic groups. In yet anotherembodiment, polycarbonate polyols are included in the polyurethanematerial of the invention. Suitable polycarbonates include, but are notlimited to, polyphthalate carbonate and poly(hexamethylene carbonate)glycol. The hydrocarbon chain can have saturated or unsaturated bonds,or substituted or unsubstituted aromatic and cyclic groups. In oneembodiment, the molecular weight of the polyol is from about 200 toabout 4000.

In a manner similar to making the above-described polyurea compositions,there are two basic techniques that can be used to make the polyurethanecompositions of this invention: a) one-shot technique, and b) prepolymertechnique. In the one-shot technique, the isocyanate blend, polyol, andhydroxyl-terminated and/or amine-terminated chain-extender (curingagent) are reacted in one step. On the other hand, the prepolymertechnique involves a first reaction between the isocyanate blend andpolyol compounds to produce a polyurethane prepolymer, and a subsequentreaction between the prepolymer and hydroxyl-terminated and/oramine-terminated chain-extender. As a result of the reaction between theisocyanate and polyol compounds, there will be some unreacted NCO groupsin the polyurethane prepolymer. The prepolymer should have less than 14%unreacted NCO groups. Preferably, the prepolymer has no greater than8.5% unreacted NCO groups, more preferably from 2.5% to 8%, and mostpreferably from 5.0% to 8.0% unreacted NCO groups. As the weight percentof unreacted isocyanate groups increases, the hardness of thecomposition also generally increases.

Either the one-shot or prepolymer method may be employed to produce thepolyurethane compositions of the invention. In one embodiment, theone-shot method is used, wherein the isocyanate compound is added to areaction vessel and then a curative mixture comprising the polyol andcuring agent is added to the reaction vessel. The components are mixedtogether so that the molar ratio of isocyanate groups to hydroxyl groupsis in the range of about 1.01:1.00 to about 1.10:1.00. Preferably, themolar ratio is greater than or equal to 1.05:1.00. For example, themolar ratio can be in the range of 1.05:1.00 to 1.10:1.00. In a secondembodiment, the prepolymer method is used. In general, the prepolymertechnique is preferred because it provides better control of thechemical reaction. The prepolymer method provides a more homogeneousmixture resulting in a more consistent polymer composition. The one-shotmethod results in a mixture that is inhomogeneous (more random) andaffords the manufacturer less control over the molecular structure ofthe resultant composition.

The polyurethane compositions can be formed by chain-extending thepolyurethane prepolymer with a single curing agent (chain-extender) orblend of curing agents (chain-extenders) as described further below. Thecompositions of the present invention may be selected from among bothcastable thermoplastic and thermoset polyurethanes. Thermoplasticpolyurethane compositions are typically formed by reacting theisocyanate blend and polyols at a 1:1 stoichiometric ratio. Thermosetcompositions, on the other hand, are cross-linked polymers and aretypically produced from the reaction of the isocyanate blend and polyolsat normally a 1.05:1 stoichiometric ratio. In general, thermosetpolyurethane compositions are easier to prepare than thermoplasticpolyurethanes.

As discussed above, the polyurethane prepolymer can be chain-extended byreacting it with a single chain-extender or blend of chain-extenders. Ingeneral, the prepolymer can be reacted with hydroxyl-terminated curingagents, amine-terminated curing agents, and mixtures thereof. The curingagents extend the chain length of the prepolymer and build-up itsmolecular weight. Normally, the prepolymer and curing agent are mixed sothe isocyanate groups and hydroxyl or amine groups are mixed at a1.05:1.00 stoichiometric ratio.

A catalyst may be employed to promote the reaction between theisocyanate and polyol compounds for producing the polyurethaneprepolymer or between the polyurethane prepolymer and chain-extenderduring the chain-extending step. Preferably, the catalyst is added tothe reactants before producing the polyurethane prepolymer. Suitablecatalysts include, but are not limited to, the catalysts described abovefor making the polyurea prepolymer. The catalyst is preferably added inan amount sufficient to catalyze the reaction of the components in thereactive mixture. In one embodiment, the catalyst is present in anamount from about 0.001 percent to about 1 percent, and preferably 0.1to 0.5 percent, by weight of the composition.

Suitable hydroxyl chain-extending (curing) agents and aminechain-extending (curing) agents include, but are not limited to, thecuring agents described above for making the polyurea andpolyurea/urethane hybrid compositions. When the polyurethane prepolymeris reacted with hydroxyl-terminated curing agents during thechain-extending step, as described above, the resulting polyurethanecomposition contains urethane linkages. On the other hand, when thepolyurethane prepolymer is reacted with amine-terminated curing agentsduring the chain-extending step, any excess isocyanate groups in theprepolymer will react with the amine groups in the curing agent. Theresulting polyurethane composition contains urethane and urea linkagesand may be referred to as a polyurethane/urea hybrid. The concentrationof urethane and urea linkages in the hybrid composition may vary. Ingeneral, the hybrid composition may contain a mixture of about 10 to 90%urethane and about 90 to 10% urea linkages.

Those layers of golf balls of the invention comprising conventionalthermoplastic or thermoset materials may be formed using a variety ofconventional application techniques such as compression molding, flipmolding, injection molding, retractable pin injection molding, reactioninjection molding (RIM), liquid injection molding (LIM), casting, vacuumforming, powder coating, flow coating, spin coating, dipping, spraying,and the like. Conventionally, compression molding and injection moldingare applied to thermoplastic materials, whereas RIM, liquid injectionmolding, and casting are employed on thermoset materials. These andother manufacture methods are disclosed in U.S. Pat. Nos. 6,207,784 and5,484,870, the disclosures of which are incorporated herein by referencein their entireties.

A method of injection molding using a split vent pin can be found inco-pending U.S. Pat. No. 6,877,974, filed Dec. 22, 2000, entitled “SplitVent Pin for Injection Molding.” Examples of retractable pin injectionmolding may be found in U.S. Pat. Nos. 6,129,881; 6,235,230; and6,379,138. These molding references are incorporated in their entiretyby reference herein. In addition, a chilled chamber, i.e., a coolingjacket, such as the one disclosed in U.S. Pat. No. 6,936,205, filed Nov.22, 2000, entitled “Method of Making Golf Balls” may be used to cool thecompositions of the invention when casting, which also allows for ahigher loading of catalyst into the system.

Golf balls of the invention include at least one compression moldedlayer comprising or consisting of any extrudate that can be preformedaccording to methods of the invention—including, for example, extrudatescomprised of rubber-based compositions. Conventionally, compressionmolding and injection molding are applied to thermoplastic materials,whereas RIM, liquid injection molding, and casting are employed onthermoset materials. These and other manufacture methods are disclosedin U.S. Pat. Nos. 5,484,870; 5,935,500; 6,207,784; 6,436,327; 7,648,667;6,562,912; 6,913,726; 7,204,946; 8,980,151; 9,211,662; U.S. Publs. Nos.2003/0067088; and 2013/0072323; the disclosures of each of which areincorporated herein by reference in their entirety.

Castable reactive liquid polyurethanes and polyurea materials may beapplied over the inner ball using a variety of application techniquessuch as casting, injection molding spraying, compression molding,dipping, spin coating, or flow coating methods that are well known inthe art. In one embodiment, the castable reactive polyurethanes andpolyurea material is formed over the core using a combination of castingand compression molding. Conventionally, compression molding andinjection molding are applied to thermoplastic cover materials, whereasRIM, liquid injection molding, and casting are employed on thermosetcover materials.

U.S. Pat. No. 5,733,428, the entire disclosure of which is herebyincorporated by reference, discloses a method for forming a polyurethanecover on a golf ball core. Because this method relates to the use ofboth casting thermosetting and thermoplastic material as the golf ballcover, wherein the cover is formed around the core by mixing andintroducing the material in mold halves, the polyurea compositions mayalso be used employing the same casting process.

For example, once a polyurea composition is mixed, an exothermicreaction commences and continues until the material is solidified aroundthe core. It is important that the viscosity be measured over time, sothat the subsequent steps of filling each mold half, introducing thecore into one half and closing the mold can be properly timed foraccomplishing centering of the core cover halves fusion and achievingoverall uniformity. A suitable viscosity range of the curing urea mixfor introducing cores into the mold halves is determined to beapproximately between about 2,000 cP and about 30,000 cP, or within arange of about 8,000 cP to about 15,000 cP.

To start the cover formation, mixing of the prepolymer and curative isaccomplished in a motorized mixer inside a mixing head by feedingthrough lines metered amounts of curative and prepolymer. Top preheatedmold halves are filled and placed in fixture units using centering pinsmoving into apertures in each mold. At a later time, the cavity of abottom mold half, or the cavities of a series of bottom mold halves, isfilled with similar mixture amounts as used for the top mold halves.After the reacting materials have resided in top mold halves for about40 to about 100 seconds, preferably for about 70 to about 80 seconds, acore is lowered at a controlled speed into the gelling reacting mixture.

A ball cup holds the shell through reduced pressure (or partial vacuum).Upon location of the core in the halves of the mold after gelling forabout 4 to about 12 seconds, the vacuum is released allowing the core tobe released. In one embodiment, the vacuum is released allowing the coreto be released after about 5 seconds to 10 seconds. The mold halves,with core and solidified cover half thereon, are removed from thecentering fixture unit, inverted and mated with second mold halveswhich, at an appropriate time earlier, have had a selected quantity ofreacting polyurea prepolymer and curing agent introduced therein tocommence gelling.

Similarly, U.S. Pat. Nos. 5,006,297 and 5,334,673 both also disclosesuitable molding techniques that may be utilized to apply the castablereactive liquids employed in the present invention.

However, golf balls of the invention may be made by any known techniqueto those skilled in the art.

Examples of yet other materials which may be suitable for incorporatingand coordinating in order to target and achieve desired playingcharacteristics or feel include plasticized thermoplastics,polyalkenamer compositions, polyester-based thermoplastic elastomerscontaining plasticizers, transparent or plasticized polyamides, thiolenecompositions, poly-amide and anhydride-modified polyolefins, organicacid-modified polymers, and the like.

The solid cores for the golf balls of this invention may be made usingany suitable conventional technique such as, for example, compression orinjection-molding, Typically, the cores are formed by compressionmolding a slug of uncured or lightly cured rubber material into aspherical structure. Prior to forming the cover layer, the corestructure may be surface-treated to increase the adhesion between itsouter surface and adjacent layer. Such surface-treatment may includemechanically or chemically-abrading the outer surface of the core. Forexample, the core may be subjected to corona-discharge,plasma-treatment, silane-dipping, or other treatment methods known tothose in the art. The cover layers are formed over the core or ballsub-assembly (the core structure and any intermediate layers disposedabout the core) using any suitable method as described further below.Prior to forming the cover layers, the ball sub-assembly may besurface-treated to increase the adhesion between its outer surface andthe overlying cover material using the above-described techniques.

Conventional compression and injection-molding and other methods can beused to form cover layers over the core or ball sub-assembly. Ingeneral, compression molding normally involves first making half(hemispherical) shells by injection-molding the composition in aninjection mold or creating preforms from exturdate. This producessemi-cured, semi-rigid half-shells (or cups). Then, the half-shells arepositioned in a compression mold around the core or ball sub-assembly.Heat and pressure are applied and the half-shells fuse together to forma cover layer over the core or sub-assembly. Compression molding alsocan be used to cure the cover composition after injection-molding. Forexample, a thermally-curable composition can be injection-molded arounda core in an unheated mold. After the composition is partially hardened,the ball is removed and placed in a compression mold. Heat and pressureare applied to the ball and this causes thermal-curing of the outercover layer.

Retractable pin injection-molding (RPIM) methods generally involve usingupper and lower mold cavities that are mated together. The upper andlower mold cavities form a spherical interior cavity when they arejoined together. The mold cavities used to form the outer cover layerhave interior dimple cavity details. The cover material conforms to theinterior geometry of the mold cavities to form a dimple pattern on thesurface of the ball. The injection-mold includes retractable supportpins positioned throughout the mold cavities. The retractable supportpins move in and out of the cavity. The support pins help maintain theposition of the core or ball sub-assembly while the molten compositionflows through the mold gates. The molten composition flows into thecavity between the core and mold cavities to surround the core and formthe cover layer. Other methods can be used to make the cover including,for example, reaction injection-molding (RIM), liquid injection-molding,casting, spraying, powder-coating, vacuum-forming, flow-coating,dipping, spin-coating, and the like.

As discussed above, an inner cover layer or intermediate layer,preferably formed from an ethylene acid copolymer ionomer composition,can be formed between the core or ball sub-assembly and cover layer. Theintermediate layer comprising the ionomer composition may be formedusing a conventional technique such as, for example, compression orinjection-molding. For example, the ionomer composition may beinjection-molded or placed in a compression mold to produce half-shells.These shells are placed around the core in a compression mold, and theshells fuse together to form an intermediate layer. Alternatively, theionomer composition is injection-molded directly onto the core usingretractable pin injection-molding.

After the golf balls have been removed from the mold, they may besubjected to finishing steps such as flash-trimming, surface-treatment,marking, and one or more coating layer may be applied as desired viamethods such as spraying, dipping, brushing, or rolling. Then the golfball can go through a series of finishing steps.

For example, in traditional white-colored golf balls, thewhite-pigmented outer cover layer may be surface-treated using asuitable method such as, for example, corona, plasma, or ultraviolet(UV) light-treatment. In another finishing process, the golf balls arepainted with one or more paint coatings. For example, white or clearprimer paint may be applied first to the surface of the ball and thenindicia may be applied over the primer followed by application of aclear polyurethane top-coat. Indicia such as trademarks, symbols, logos,letters, and the like may be printed on the outer cover or prime-coatedlayer, or top-coated layer using pad-printing, ink-jet printing,dye-sublimation, or other suitable printing methods. Any of the surfacecoatings may contain a fluorescent optical brightener.

The golf balls of this invention provide the ball with a variety ofadvantageous mechanical and playing performance properties as discussedfurther below. In general, the hardness, diameter, and thickness of thedifferent ball layers may vary depending upon the desired ballconstruction. Thus, golf balls of the invention may have any knownoverall diameter and any known number of different layers and layerthicknesses, wherein the inventive compression molded layer isincorporated in one or more outer layers in order to target desiredplaying characteristics.

For example, the core may have a diameter ranging from about 0.09 inchesto about 1.65 inches. In one embodiment, the diameter of the core of thepresent invention is about 1.2 inches to about 1.630 inches. When partof a two-piece ball according to invention, the core may have a diameterranging from about 1.5 inches to about 1.62 inches. In anotherembodiment, the diameter of the core is about 1.3 inches to about 1.6inches, preferably from about 1.39 inches to about 1.6 inches, and morepreferably from about 1.5 inches to about 1.6 inches. In yet anotherembodiment, the core has a diameter of about 1.55 inches to about 1.65inches, preferably about 1.55 inches to about 1.60 inches.

In some embodiments, the core may have an overall diameter within arange having a lower limit of 0.500 or 0.700 or 0.750 or 0.800 or 0.850or 0.900 or 0.950 or 1.000 or 1.100 or 1.150 or 1.200 or 1.250 or 1.300or 1.350 or 1.400 or 1.450 or 1.500 or 1.600 or 1.610 inches and anupper limit of 1.620 or 1.630 or 1.640 inches. In a particularembodiment, the core is a multi-layer core having an overall diameterwithin a range having a lower limit of 0.500 or 0.700 or 0.750 or 0.800or 0.850 or 0.900 or 0.950 or 1.000 or 1.100 or 1.150 or 1.200 inchesand an upper limit of 1.250 or 1.300 or 1.350 or 1.400 or 1.450 or 1.500or 1.600 or 1.610 or 1.620 or 1.630 or 1.640 inches. In anotherparticular embodiment, the multi-layer core has an overall diameterwithin a range having a lower limit of 0.500 or 0.700 or 0.750 inchesand an upper limit of 0.800 or 0.850 or 0.900 or 0.950 or 1.000 or 1.100or 1.150 or 1.200 or 1.250 or 1.300 or 1.350 or 1.400 or 1.450 or 1.500or 1.600 or 1.610 or 1.620 or 1.630 or 1.640 inches. In anotherparticular embodiment, the multi-layer core has an overall diameter of1.500 inches or 1.510 inches or 1.530 inches or 1.550 inches or 1.570inches or 1.580 inches or 1.590 inches or 1.600 inches or 1.610 inchesor 1.620 inches.

In some embodiments, the inner core can have an overall diameter of0.500 inches or greater, or 0.700 inches or greater, or 1.00 inches orgreater, or 1.250 inches or greater, or 1.350 inches or greater, or1.390 inches or greater, or 1.450 inches or greater, or an overalldiameter within a range having a lower limit of 0.250 or 0.500 or 0.750or 1.000 or 1.250 or 1.350 or 1.390 or 1.400 or 1.440 inches and anupper limit of 1.460 or 1.490 or 1.500 or 1.550 or 1.580 or 1.600inches, or an overall diameter within a range having a lower limit of0.250 or 0.300 or 0.350 or 0.400 or 0.500 or 0.550 or 0.600 or 0.650 or0.700 inches and an upper limit of 0.750 or 0.800 or 0.900 or 0.950 or1.000 or 1.100 or 1.150 or 1.200 or 1.250 or 1.300 or 1.350 or 1.400inches.

In some embodiments, the outer core layer can have an overall thicknesswithin a range having a lower limit of 0.010 or 0.020 or 0.025 or 0.030or 0.035 inches and an upper limit of 0.040 or 0.070 or 0.075 or 0.080or 0.100 or 0.150 inches, or an overall thickness within a range havinga lower limit of 0.025 or 0.050 or 0.100 or 0.150 or 0.160 or 0.170 or0.200 inches and an upper limit of 0.225 or 0.250 or 0.275 or 0.300 or0.325 or 0.350 or 0.400 or 0.450 or greater than 0.450 inches. The outercore layer may alternatively have a thickness of greater than 0.10inches, or 0.20 inches or greater, or greater than 0.20 inches, or 0.30inches or greater, or greater than 0.30 inches, or 0.35 inches orgreater, or greater than 0.35 inches, or 0.40 inches or greater, orgreater than 0.40 inches, or 0.45 inches or greater, or greater than0.45 inches, or a thickness within a range having a lower limit of 0.005or 0.010 or 0.015 or 0.020 or 0.025 or 0.030 or 0.035 or 0.040 or 0.045or 0.050 or 0.055 or 0.060 or 0.065 or 0.070 or 0.075 or 0.080 or 0.090or 0.100 or 0.200 or 0.250 inches and an upper limit of 0.300 or 0.350or 0.400 or 0.450 or 0.500 or 0.750 inches.

An intermediate core layer can have any known overall thickness such aswithin a range having a lower limit of 0.005 or 0.010 or 0.015 or 0.020or 0.025 or 0.030 or 0.035 or 0.040 or 0.045 inches and an upper limitof 0.050 or 0.055 or 0.060 or 0.065 or 0.070 or 0.075 or 0.080 or 0.090or 0.100 inches.

The cores and core layers of golf balls of the invention may havevarying hardnesses depending on the particular golf ball constructionand playing characteristics being targeted. Core center and/or layerhardness can range, for example, from 35 Shore C to about 98 Shore C, or50 Shore C to about 90 Shore C, or 60 Shore C to about 85 Shore C, or 45Shore C to about 75 Shore C, or 40 Shore C to about 85 Shore C. In otherembodiments, core center and/or layer hardness can range, for example,from about 20 Shore D to about 78 Shore D, or from about 30 Shore D toabout 60 Shore D, or from about 40 Shore D to about 50 Shore D, or 50Shore D or less, or greater than 50 Shore D.

The compression of the core is generally overall in the range of about40 to about 110, although embodiments are envisioned wherein thecompression of the core is as low as 5. In other embodiments, theoverall CoR of cores of the present invention at 125 ft/s is at least0.750, or at least 0.775 or at least 0.780, or at least 0.785, or atleast 0.790, or at least 0.795, or at least 0.800. Cores are also knownto comprise rubbers and also may be formed of a variety of othermaterials that are typically also used for intermediate and coverlayers. Intermediate layers may likewise also comprise materialsgenerally used in cores and covers as described herein for example.

An intermediate layer is sometimes thought of as including any layer(s)disposed between the inner core (or center) and the outer cover of agolf ball, and thus in some embodiments, the intermediate layer mayinclude an outer core layer, a casing/mantle layer, and/or inner coverlayer(s). In this regard, a golf ball of the invention may include oneor more intermediate layers. An intermediate layer may be used, ifdesired, with a multilayer cover or a multilayer core, or with both amultilayer cover and a multilayer core.

In one non-limiting embodiment, an intermediate layer having a thicknessof about 0.010 inches to about 0.06 inches, is disposed about a corehaving a diameter ranging from about 1.5 inches to about 1.59 inches.

Intermediate layer(s) may be formed, at least in part, from one or morehomopolymeric or copolymeric materials, such as ionomers, primarily orfully non-ionomeric thermoplastic materials, vinyl resins, polyolefins,polyurethanes, polyureas, polyamides, acrylic resins and blends thereof,olefinic thermoplastic rubbers, block copolymers of styrene andbutadiene, isoprene or ethylene-butylene rubber, copoly(ether-amide),polyphenylene oxide resins or blends thereof, and thermoplasticpolyesters. However, embodiments are envisioned wherein at least oneintermediate layer is formed from a different material commonly used ina core and/or cover layer.

The range of thicknesses for an intermediate layer of a golf ball islarge because of the vast possibilities when using an intermediatelayer, i.e., as an outer core layer, an inner cover layer, a woundlayer, a moisture/vapor barrier layer. When used in a golf ball of thepresent invention, the intermediate layer, or inner cover layer, mayhave a thickness about 0.3 inches or less. In one embodiment, thethickness of the intermediate layer is from about 0.002 inches to about0.1 inches, and preferably about 0.01 inches or greater.

For example, when part of a three-piece ball or multi-layer ballaccording to the invention, the intermediate layer and/or inner coverlayer may have a thickness ranging from about 0.010 inches to about 0.06inches. In another embodiment, the intermediate layer thickness is about0.05 inches or less, or about 0.01 inches to about 0.045 inches forexample.

If the ball includes an intermediate layer or inner cover layer, thehardness (material) may for example be about 50 Shore D or greater, morepreferably about 55 Shore D or greater, and most preferably about 60Shore D or greater. In one embodiment, the inner cover has a Shore Dhardness of about 62 to about 90 Shore D. In one example, the innercover has a hardness of about 68 Shore D or greater. In addition, thethickness of the inner cover layer is preferably about 0.015 inches toabout 0.100 inches, more preferably about 0.020 inches to about 0.080inches, and most preferably about 0.030 inches to about 0.050 inches,but once again, may be changed to target playing characteristics.

The cover typically has a thickness to provide sufficient strength, goodperformance characteristics, and durability. In one embodiment, thecover thickness may for example be from about 0.02 inches to about 0.12inches, or about 0.1 inches or less. For example, the cover may be partof a two-piece golf ball and have a thickness ranging from about 0.03inches to about 0.09 inches. In another embodiment, the cover thicknessmay be about 0.05 inches or less, or from about 0.02 inches to about0.05 inches, or from about 0.02 inches and about 0.045 inches.

The cover may be a single-, dual-, or multi-layer cover and have anoverall thickness for example within a range having a lower limit of0.010 or 0.020 or 0.025 or 0.030 or 0.040 or 0.045 inches and an upperlimit of 0.050 or 0.060 or 0.070 or 0.075 or 0.080 or 0.090 or 0.100 or0.150 or 0.200 or 0.300 or 0.500 inches. In a particular embodiment, thecover may be a single layer having a thickness of from 0.010 or 0.020 or0.025 inches to 0.035 or 0.040 or 0.050 inches. In another particularembodiment, the cover may consist of an inner cover layer having athickness of from 0.010 or 0.020 or 0.025 inches to 0.035 or 0.050inches and an outer cover layer having a thickness of from 0.010 or0.020 or 0.025 inches to 0.035 or 0.040 inches.

The outer cover preferably has a thickness within a range having a lowerlimit of about 0.004 or 0.010 or 0.020 or 0.030 or 0.040 inches and anupper limit of about 0.050 or 0.055 or 0.065 or 0.070 or 0.080 inches.Preferably, the thickness of the outer cover is about 0.020 inches orless. The outer cover preferably has a surface hardness of 75 Shore D orless, 65 Shore D or less, or 55 Shore D or less, or 50 Shore D or less,or 50 Shore D or less, or 45 Shore D or less. Preferably, the outercover has hardness in the range of about 20 to about 70 Shore D. In oneexample, the outer cover has hardness in the range of about 25 to about65 Shore D.

In one embodiment, the cover may be a single layer having a surfacehardness for example of 60 Shore D or greater, or 65 Shore D or greater.In a particular aspect of this embodiment, the cover is formed from acomposition having a material hardness of 60 Shore D or greater, or 65Shore D or greater.

In another particular embodiment, the cover may be a single layer havinga thickness of from 0.010 or 0.020 inches to 0.035 or 0.050 inches andformed from a composition having a material hardness of from 60 or 62 or65 Shore D to 65 or 70 or 72 Shore D.

In yet another particular embodiment, the cover is a single layer havinga thickness of from 0.010 or 0.025 inches to 0.035 or 0.040 inches andformed from a composition having a material hardness of 62 Shore D orless, or less than 62 Shore D, or 60 Shore D or less, or less than 60Shore D, or 55 Shore D or less, or less than 55 Shore D.

In still another particular embodiment, the cover is a single layerhaving a thickness of from 0.010 or 0.025 inches to 0.035 or 0.040inches and formed from a composition having a material hardness of 62Shore D or less, or less than 62 Shore D, or 60 Shore D or less, or lessthan 60 Shore D, or 55 Shore D or less, or less than 55 Shore D.

In an alternative embodiment, the cover may comprise an inner coverlayer and an outer cover layer. The inner cover layer composition mayhave a material hardness of from 60 or 62 or 65 Shore D to 65 or 70 or72 Shore D. The inner cover layer may have a thickness within a rangehaving a lower limit of 0.010 or 0.020 or 0.030 inches and an upperlimit of 0.035 or 0.040 or 0.050 inches. The outer cover layercomposition may have a material hardness of 62 Shore D or less, or lessthan 62 Shore D, or 60 Shore D or less, or less than 60 Shore D, or 55Shore D or less, or less than 55 Shore D. The outer cover layer may havea thickness within a range having a lower limit of 0.010 or 0.020 or0.025 inches and an upper limit of 0.035 or 0.040 or 0.050 inches.

In yet another embodiment, the cover is a dual- or multi-layer coverincluding an inner or intermediate cover layer and an outer cover layer.The inner cover layer may have a surface hardness of 70 Shore D or less,or 65 Shore D or less, or less than 65 Shore D, or a Shore D hardness offrom 50 to 65, or a Shore D hardness of from 57 to 60, or a Shore Dhardness of 58, and a thickness within a range having a lower limit of0.010 or 0.020 or 0.030 inches and an upper limit of 0.045 or 0.080 or0.120 inches. The outer cover layer may have a material hardness of 65Shore D or less, or 55 Shore D or less, or 45 Shore D or less, or 40Shore D or less, or from 25 Shore D to 40 Shore D, or from 30 Shore D to40 Shore D. The outer cover layer may have a surface hardness within arange having a lower limit of 20 or 30 or 35 or 40 Shore D and an upperlimit of 52 or 58 or 60 or 65 or 70 or 72 or 75 Shore D. The outer coverlayer may have a thickness within a range having a lower limit of 0.010or 0.015 or 0.025 inches and an upper limit of 0.035 or 0.040 or 0.045or 0.050 or 0.055 or 0.075 or 0.080 or 0.115 inches.

All this being said, embodiments are also envisioned wherein one or moreof the cover layers is formed from a material typically incorporated ina core or intermediate layer.

It is envisioned that golf balls of the invention may also incorporateconventional coating layer(s) for the purposes usually incorporated. Forexample, one or more coating layer may have a combined thickness of fromabout 0.1 μm to about 100 μm, or from about 2 μm to about 50 μm, or fromabout 2 μm to about 30 μm. Meanwhile, each coating layer may have athickness of from about 0.1 μm to about 50 μm, or from about 0.1 μm toabout 25 μm, or from about 0.1 μm to about 14 μm, or from about 2 μm toabout 9 μm, for example.

It is envisioned that layers a golf ball of the invention other than theinventive compression molded layer may be incorporated via any ofcasting, compression molding, injection molding, or thermoforming.

The resulting balls of this invention have good impact durability andcut/shear-resistance. The United States Golf Association (“USGA”) hasset total weight limits for golf balls. Particularly, the USGA hasestablished a maximum weight of 45.93 g (1.62 ounces) for golf balls.There is no lower weight limit. In addition, the USGA requires that golfballs used in competition have a diameter of at least 1.68 inches. Thereis no upper limit so many golf balls have an overall diameter fallingwithin the range of about 1.68 to about 1.80 inches. The golf balldiameter is preferably about 1.68 to 1.74 inches, more preferably about1.68 to 1.70 inches. In accordance with the present invention, theweight, diameter, and thickness of the core and cover layers may beadjusted, as needed, so the ball meets USGA specifications of a maximumweight of 1.62 ounces and a minimum diameter of at least 1.68 inches.

Preferably, the golf ball has a Coefficient of Restitution (CoR) of atleast 0.750 and more preferably at least 0.800 (as measured per the testmethods below). The core of the golf ball generally has a compression inthe range of about 30 to about 130 and more preferably in the range ofabout 70 to about 110 (as measured per the test methods below.) Theseproperties allow players to generate greater ball velocity off the teeand achieve greater distance with their drives. At the same time, therelatively thin outer cover layer means that a player will have a morecomfortable and natural feeling when striking the ball with a club. Theball is more playable and its flight path can be controlled more easily.This control allows the player to make better approach shots near thegreen. Furthermore, the outer covers of this invention have good impactdurability and mechanical strength.

The following test methods may be used to obtain certain properties inconnection with golf balls of the invention and layers thereof.

Hardness.

The center hardness of a core is obtained according to the followingprocedure. The core is gently pressed into a hemispherical holder havingan internal diameter approximately slightly smaller than the diameter ofthe core, such that the core is held in place in the hemispherical ofthe holder while concurrently leaving the geometric central plane of thecore exposed. The core is secured in the holder by friction, such thatit will not move during the cutting and grinding steps, but the frictionis not so excessive that distortion of the natural shape of the corewould result. The core is secured such that the parting line of the coreis roughly parallel to the top of the holder. The diameter of the coreis measured 90 degrees to this orientation prior to securing. Ameasurement is also made from the bottom of the holder to the top of thecore to provide a reference point for future calculations. A rough cutis made slightly above the exposed geometric center of the core using aband saw or other appropriate cutting tool, making sure that the coredoes not move in the holder during this step. The remainder of the core,still in the holder, is secured to the base plate of a surface grindingmachine. The exposed ‘rough’ surface is ground to a smooth, flatsurface, revealing the geometric center of the core, which can beverified by measuring the height from the bottom of the holder to theexposed surface of the core, making sure that exactly half of theoriginal height of the core, as measured above, has been removed towithin 0.004 inches. Leaving the core in the holder, the center of thecore is found with a center square and carefully marked and the hardnessis measured at the center mark according to ASTM D-2240. Additionalhardness measurements at any distance from the center of the core canthen be made by drawing a line radially outward from the center mark,and measuring the hardness at any given distance along the line,typically in 2 mm increments from the center. The hardness at aparticular distance from the center should be measured along at leasttwo, preferably four, radial arms located 180° apart, or 90° apart,respectively, and then averaged. All hardness measurements performed ona plane passing through the geometric center are performed while thecore is still in the holder and without having disturbed itsorientation, such that the test surface is constantly parallel to thebottom of the holder, and thus also parallel to the properly alignedfoot of the durometer.

The outer surface hardness of a golf ball layer is measured on theactual outer surface of the layer and is obtained from the average of anumber of measurements taken from opposing hemispheres, taking care toavoid making measurements on the parting line of the core or on surfacedefects, such as holes or protrusions. Hardness measurements are madepursuant to ASTM D-2240 “Indentation Hardness of Rubber and Plastic byMeans of a Durometer.” Because of the curved surface, care must be takento ensure that the golf ball or golf ball sub-assembly is centered underthe durometer indenter before a surface hardness reading is obtained. Acalibrated, digital durometer, capable of reading to 0.1 hardness unitsis used for the hardness measurements. The digital durometer must beattached to, and its foot made parallel to, the base of an automaticstand. The weight on the durometer and attack rate conforms to ASTMD-2240.

In certain embodiments, a point or plurality of points measured alongthe “positive” or “negative” gradients may be above or below a line fitthrough the gradient and its outermost and innermost hardness values. Inan alternative preferred embodiment, the hardest point along aparticular steep “positive” or “negative” gradient may be higher thanthe value at the innermost of the inner core (the geometric center) orouter core layer (the inner surface)—as long as the outermost point(i.e., the outer surface of the inner core) is greater than (for“positive”) or lower than (for “negative”) the innermost point (i.e.,the geometric center of the inner core or the inner surface of the outercore layer), such that the “positive” and “negative” gradients remainintact.

As discussed above, the direction of the hardness gradient of a golfball layer is defined by the difference in hardness measurements takenat the outer and inner surfaces of a particular layer. The centerhardness of an inner core and hardness of the outer surface of an innercore in a single-core ball or outer core layer are readily determinedaccording to the test procedures provided above. The outer surface ofthe inner core layer (or other optional intermediate core layers) in adual-core ball are also readily determined according to the proceduresgiven herein for measuring the outer surface hardness of a golf balllayer, if the measurement is made prior to surrounding the layer with anadditional core layer. Once an additional core layer surrounds a layerof interest, the hardness of the inner and outer surfaces of any inneror intermediate layers can be difficult to determine. Therefore, forpurposes of the present invention, when the hardness of the inner orouter surface of a core layer is needed after the inner layer has beensurrounded with another core layer, the test procedure described abovefor measuring a point located 1 mm from an interface is used.

Also, it should be understood that there is a fundamental differencebetween “material hardness” and “hardness as measured directly on a golfball.” For purposes of the present invention, material hardness ismeasured according to ASTM D2240 and generally involves measuring thehardness of a flat “slab” or “button” formed of the material. Surfacehardness as measured directly on a golf ball (or other sphericalsurface) typically results in a different hardness value. The differencein “surface hardness” and “material hardness” values is due to severalfactors including, but not limited to, ball construction (that is, coretype, number of cores and/or cover layers, and the like); ball (orsphere) diameter; and the material composition of adjacent layers. Italso should be understood that the two measurement techniques are notlinearly related and, therefore, one hardness value cannot easily becorrelated to the other. Shore hardness (for example, Shore C or Shore Dor Shore A hardness) was measured according to the test method ASTMD-2240.

Modulus, Tensile Strength and Ultimate Elongation

Modulus, tensile strength and ultimate elongation of golf ball layermaterials may be targeted as known in the art. As used herein, “modulus”or “flexural modulus” refers to flexural modulus as measured using astandard flex bar according to ASTM D790-B; tensile strength refers totensile strength as measured using ASTM D-638; and ultimate elongationrefers to ultimate elongation as measured using ASTM D-638.

Compression.

As disclosed in Jeff Dalton's Compression by Any Other Name, Science andGolf IV, Proceedings of the World Scientific Congress of Golf (EricThain ed., Routledge, 2002) (“J. Dalton”), several different methods canbe used to measure compression, including Atti compression, Riehlecompression, load/deflection measurements at a variety of fixed loadsand offsets, and effective modulus. For purposes of the presentinvention, compression refers to Soft Center Deflection Index (“SCDI”).The SCDI is a program change for the Dynamic Compression Machine (“DCM”)that allows determination of the pounds required to deflect a core 10%of its diameter. The DCM is an apparatus that applies a load to a coreor ball and measures the number of inches the core or ball is deflectedat measured loads. A crude load/deflection curve is generated that isfit to the Atti compression scale that results in a number beinggenerated that represents an Atti compression. The DCM does this via aload cell attached to the bottom of a hydraulic cylinder that istriggered pneumatically at a fixed rate (typically about 1.0 ft/s)towards a stationary core. Attached to the cylinder is an LVDT thatmeasures the distance the cylinder travels during the testing timeframe.A software-based logarithmic algorithm ensures that measurements are nottaken until at least five successive increases in load are detectedduring the initial phase of the test. The SCDI is a slight variation ofthis set up. The hardware is the same, but the software and output haschanged. With the SCDI, the interest is in the pounds of force requiredto deflect a core×amount of inches. That amount of deflection is 10%percent of the core diameter. The DCM is triggered, the cylinderdeflects the core by 10% of its diameter, and the DCM reports back thepounds of force required (as measured from the attached load cell) todeflect the core by that amount. The value displayed is a single numberin units of pounds.

Coefficient of Restitution (“CoR”).

The CoR is determined according to a known procedure, wherein a golfball or golf ball sub-assembly (for example, a golf ball core) is firedfrom an air cannon at two given velocities and a velocity of 125 ft/s isused for the calculations. Ballistic light screens are located betweenthe air cannon and steel plate at a fixed distance to measure ballvelocity. As the ball travels toward the steel plate, it activates eachlight screen and the ball's time period at each light screen ismeasured. This provides an incoming transit time period which isinversely proportional to the ball's incoming velocity. The ball makesimpact with the steel plate and rebounds so it passes again through thelight screens. As the rebounding ball activates each light screen, theball's time period at each screen is measured. This provides an outgoingtransit time period which is inversely proportional to the ball'soutgoing velocity. The CoR is then calculated as the ratio of the ball'soutgoing transit time period to the ball's incoming transit time period(CoR=V_(out)/V_(in)=T_(in)/T_(out)).

Thermoset and thermoplastic layers herein may be treated in such amanner as to create a positive or negative hardness gradient within andbetween golf ball layers. In golf ball layers of the present inventionwherein a thermosetting rubber is used, gradient-producing processesand/or gradient-producing rubber formulation may be employed.Gradient-producing processes and formulations are disclosed more fully,for example, in U.S. patent application Ser. No. 12/048,665, filed onMar. 14, 2008; Ser. No. 11/829,461, filed on Jul. 27, 2007; Ser. No.11/772,903, filed Jul. 3, 2007; Ser. No. 11/832,163, filed Aug. 1, 2007;Ser. No. 11/832,197, filed on Aug. 1, 2007; the entire disclosure ofeach of these references is hereby incorporated herein by reference.

It is understood that the golf balls of the invention incorporatinginventive half-shells comprised of inventive preforms and methods andtooling for making as described and illustrated herein represent onlysome of the many embodiments of the invention. It is appreciated bythose skilled in the art that various changes and additions can be madeto such golf balls without departing from the spirit and scope of thisinvention. It is intended that all such embodiments be covered by theappended claims.

A golf ball of the invention may further incorporate indicia, which asused herein, is considered to mean any symbol, letter, group of letters,design, or the like, that can be added to the dimpled surface of a golfball.

Golf balls of the present invention will typically have dimple coverageof 60% or greater, preferably 65% or greater, and more preferably 75% orgreater. It will be appreciated that any known dimple pattern may beused with any number of dimples having any shape or size. For example,the number of dimples may be 252 to 456, or 330 to 392 and may compriseany width, depth, and edge angle. The parting line configuration of saidpattern may be either a straight line or a staggered wave parting line(SWPL), for example.

In any of these embodiments the single-layer core may be replaced with atwo or more layer core wherein at least one core layer has a hardnessgradient.

Other than in the operating examples, or unless otherwise expresslyspecified, all of the numerical ranges, amounts, values and percentagessuch as those for amounts of materials and others in the specificationmay be read as if prefaced by the word “about” even though the term“about” may not expressly appear with the value, amount or range.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the specification and attached claims are approximationsthat may vary depending upon the desired properties sought to beobtained by the present invention. At the very least, and not as anattempt to limit the application of the doctrine of equivalents to thescope of the claims, each numerical parameter should at least beconstrued in light of the number of reported significant digits and byapplying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Furthermore, when numerical ranges ofvarying scope are set forth herein, it is contemplated that anycombination of these values inclusive of the recited values may be used.

Although the golf ball of the invention has been described herein withreference to particular means and materials, it is to be understood thatthe invention is not limited to the particulars disclosed and extends toall equivalents within the scope of the claims.

It is understood that the manufacturing methods, compositions,constructions, and products described and illustrated herein representonly some embodiments of the invention. It is appreciated by thoseskilled in the art that various changes and additions can be made tocompositions, constructions, and products without departing from thespirit and scope of this invention. It is intended that all suchembodiments be covered by the appended claims.

The invention claimed is:
 1. A method of making a golf ball comprisingthe steps of: providing a length of extrudate having a width sufficientto be received within first and second half-shell molding cups;cross-sectioning the extrudate at predetermined intervals along thelength while progressing the extrudate along a plane that isperpendicular to a plane of rotation of a curved flying knife andforming a plurality of preforms, each having a cross-sectioned surfacethat is concave and curves inward toward a posterior end of the preforma curved depth that is greater than a depth created by a straight edgeflying knife; wherein the curved flying knife comprises: an elongatedbody defining an inner end and a distal end; the inner end beingrotatably connectable to a device for cross-sectioning a length ofextrudate into a plurality of preforms; a curved edge located on a firstside of the elongated body and an opposing edge located on the oppositeside of the elongated body; wherein each of the curved edge and theopposing edge extend between the inner end and distal end; and whereinthe curved edge curves away from the opposing edge at least at alocation on the first side that contacts the extrudate andcross-sections it; and depositing first and second preforms into a golfball component mold, loading the mold into a mold press, closing themold press, and forming first and second half-shell molding cups undersufficient heat and pressure; wherein the cross-sectioned surfaces ofthe first and second preforms are face up in the golf ball componentmold and form an inner surface of each half shell molding cup; andmating first and second half-shell molding cups about a subassemblyunder sufficient heat and pressure.
 2. The method of making a golf ballof claim 1, wherein the curved depth is greater than the depth by up to20%.
 3. The method of making a golf ball of claim 2, wherein thesubassembly is a rubber inner core and the outer layer is a rubber outercore layer.
 4. The method of making a golf ball of claim 3, wherein therubber of the inner core and the rubber of the outer core layer differ.5. A method of making a golf ball comprising the steps of: providing alength of extrudate having a width sufficient to be received withinfirst and second half-shell molding cups; cross-sectioning the extrudateat predetermined intervals along the length while progressing theextrudate along a plane that is perpendicular to a plane of rotation ofa curved flying knife and forming a plurality of preforms, each having across-sectioned surface that is concave and curves inward toward aposterior end of the preform a curved depth that is greater than a depthcreated by a straight edge flying knife; wherein the curved flying knifecomprises: an elongated body defining an inner end and a distal end; theinner end being rotatably connectable to a device for cross-sectioning alength of extrudate into a plurality of preforms; a curved face locatedon the elongated body between a bladed edge and an opposing edge;wherein each of the bladed edge and the opposing edge co-extend from thedistal end toward the inner end a predetermined length and follow acontour of the curved face; and wherein the curved face curves towardthe extrudate while the bladed edge cross-sections the extrudate; anddepositing first and second preforms into a golf ball component mold,loading the mold into a mold press, closing the mold press, and formingfirst and second half-shell molding cups under sufficient heat andpressure; wherein the cross-sectioned surfaces of the first and secondpreforms are face up in the golf ball component mold and form an innersurface of each half shell molding cup; and mating first and secondhalf-shell molding cups about a subassembly under sufficient heat andpressure.
 6. The method of claim 5, wherein the bladed edge is straightedged.
 7. The method of claim 5, wherein the bladed edge is a curvededge that curves away from the opposing edge and contacts the extrudateand cross-sections it.